PC Flashing & Brick Recovery

WARNING: Always make a backup of your current, working firmware before flashing anything via PC. In case of wrong firmware (e.g. wrong included display driver) it may very hard to get it working again without correct firmware. It is always recommended to keep a working backup. See here. Do Simple System BackUp at minimum.

Newer HU maybe easier to brick Read here.

Firmware format and installation diagrams

Here is a general overview diagram providing an understanding of OTA, firmware, and TWRP flashing. And flashing upgrade to 64bit on <= 4GB HUs:
https://mega.nz/folder/hDEhFAqZ#A0JuPIKhW83X5NZgL2NSWg/folder/QTllgKwA

Tools needed for PC flashing or brick recovery

• Windows 7, 8.1 , 10 or 11 to run flashing software. Linux may also work, but has not been tested.

• SIM tray tool or paperclip for triggering "RST" (reset).

• For PC flashing:
  - USB cable with USB-A male end to HU and the other end to the PC (USB-A or USB-C). Some older thread says <= 1m. I used ~2m and very old (from USB 1&2 era) and worked fine. Someone needed to use a Y cable to have enough power for flashing (see here at XDA). I guess this maybe PC USB port power level dependent. Most people seem to not encounter this problem.
  - SP Flash Tool 5 (Important: version 5, not version 6)
  - MTK Driver. Install the driver with admin privilege (not sure if necessary). Installation may ask if want to remove USB drivers. Click "Okay" (it's only removing previously installed Flash Tool drivers, doesn't touch any other USB drivers). Let it finish and reboot Windows. I had to prompt the installation with return key a couple of times to get it to finish.
  Only for Windows 7 and 8.1: If installation of driver fails when connecting HU to PC, uninstall MTK Driver, install archived version 5.1632 and reboot Windows.

• Only needed for some brick recoverys: FAT32 formatted USB stick, although I've used 64GB exFAT without problems.

Bricking

5 ways to brick the HU

1. Install the UI with fix resolution different than your HU.

2. Install wrong firmware which is unable to display or used wrong display driver.

3. Install wrong firmware that doesn't run at all.

4. Install the wrong preloader and unable to connect to PC to flash firmware.

5. Install the wrong metazone (not sure if it really bricks HU).

#1 & #2 can be recovered by display driver recovery method. #3 require full flash of firmware into flash memory. #4 require disassemble hardware and find the test points (see Bricked and unable to connect to PC to flash firmware).

Major cause of display bricking

There are many logo(.mrf) files, one for each LCD panel model. This is a major cause for display bricking. Read here

Simple ways to help online community

Please read this section after unbricking your HU: Helping the community. Very easy to contribute back useful information. Only takes a few seconds and one post.

Already bricked and unknown HU version

This is the most challenging case if do not have original "Car Settings" -> "System Info" screen to show which HU version and firmware type. This image also can match others found online to determine HU firmware maker.

There are many HU variations and multiple firmware makers (read here and here).

Maybe the mainboard will offer some clues although many look the same. Even board # printed on logic board may not match the actual HU version. But matching exactly same looking boards with others maybe the only solution. I've seem some with XYAUTO stickers, stickers with model # on the connector block, MCU version #, and logic board has printed board # and versions (link, link, link).

If the HU seems to boot complete but not display properly, I don't know if there are ways via USB port to see what version of HU. A blank USB stick might get the "Android" folder but may not have valuable clue inside. I don't know if connecting USB port to a computer running terminal application will see any kind of boot logging info that may offer clues.

Bricked and unable to connect to PC to flash firmware

Most likely wrong preloader was flashed in prior attempt. Recovery require opening HU logic board and find test point to flash in correct preloader. Here's how to proceed (credits go to polarfest at XDA):

1. Locate KPCOLO test point (see images in post #1,924 at XDA), there is an RF shield that needs to be removed.

2. Attach a strip of wire to a ground point like GPS or Radio Antenna on the board.

3. Launch download process in SP Flashing Tool, it will wait for HU to be ready.

4. Using the wire from step 2 ground KPCOLO test point and power the unit, a windows chime should indicate a detected USB device and flashing software should upload preloader.bin in a few seconds.

5. Once flashing tool is complete unit should be back to live and continue with regular flashing process.

Read also this post, which is also the source of the tutorial above:
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88668467

Wrong display driver recovery

Background information:
Bricked display is due to flashing the wrong display driver ( has logo.mrf file inside ) to the HU. When the wrong one for the display is flashed, you'll get a black screen or you'll recognize other strange phenomenon. It should be clear that without working display there is a huge problem that can't be solved with a few easy settings. In this case a correct display driver needs to be flashed. Read here for background on logo.mrf 

Here is how to determine if this is your brick condition and how to recover:

1. Some car's accessory mode will shutoff radio after few minutes. To prevent this problem, it's best to start the car while patching/flashing any firmware. This is especially important in longer duration processes like this one.

2. Confirm firmware on HU is running correctly to verify that the display driver is wrong. There are 2 ways to confirm HU booted the firmware correctly but has the wrong display driver so screen is blank. Probably best to confirm both ways.
   1. If HU backlight is on, then firmware booted correctly on HU and just can not display due to wrong display driver. If no backlight on, then firmware didn't boot and will need to recovery another way.
   2. Insert freshly formatted FAT32 (macOS FAT=FAT32) and MBR or GUID partition table  (exFAT may also work) USB stick (without "Android" folder) into USB port (try both). Wait at least 15-20 seconds and remove. Check if "Android" folder appears. If so, then HU is running firmware properly and added this folder when it detected the USB stick insertion. In case this doesn't work, also try to reboot HU (push RST button) and see if it appears.

3. Find display drivers:

Read here

4. Put 2 files on FAT32 USB stick:

   1. XYAUTO_UPDATE.bin -> XYAUTO has removed their public access, post #104 at XDA archived this file, which is a blank file and the HU only seems to be triggered to update by the filename. If you do find this file In XYAUTO's file folder, there are other bin files including xyauto_upgrade.bin, which has similar name to XYAUTO_UPDATE.bin, but in lower case. Don't touch these other bin files.

   2. Display Driver .gz file found from prior step/

   3. Power up the HU without display. Insert the USB (try both) with the 2 files. HU will auto detect XYAUTO_UPDATE and trigger the update process of whatever update file is on the USB stick. Video of successful effort (link)

5. If the above Display Driver doesn't work, then you may have the wrong driver on the FAT32 USB stick. Try others.

6. Please read this section: Helping the community. Very easy to contribute back useful information. Only takes a few seconds and one post.

Source: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88195579

Flash firmware (1.73.8+/1.80.1+ upgrade or brick recovery) via PC

General overview diagram here.

Warnings

1. This guide is for YT5760B (HU ID) only. AC8257/AC8259 is the chipset name. There are other HUs with different firmware makers using this chip. If flashing YT5760B firmware into other HUs, it will brick and likely difficult to recover after wrong preloader is installed (will likely disable ability to flash again even after finding correct firmware), read here.

2. If wrong preloader (there are 4) is used, then PC will not be able to connect and flash further. So be sure to choose the correct preloader file. Read about preloaders later in the flashing procedures.

3. xyauto firmware will not include all necessary files. One missing file in particular ( logo.mrf ) has many versions and wrong one will brick the display. Make sure familiarize how to get the correct logo.mrf through backup process. Otherwise, may display brick and need to try many archived display drivers for recovery ( A possible risk is your HU's driver may not exist in the archive)

4. Format and flashing new firmware will erase IMEI, activation codes and 360 camera calibration data. See here how to save them before flashing.

5. This guide was tested with 5760B 2GB 1024x600 HU and 5760B 8GB 1024x600 HU. For other models, please search and check for past success. This database include some links to flash results on other models (e.g. 7260B). Other display resolutions may brick display (e.g. in the past were problems with 1280x720 displays) So always make a backup of a working firmware before flashing anything

6. Some legacy warnings for older firmware are in this post at XDA.

Simple ways to help online community

Please read this section: Helping the community. Very easy to contribute back useful information. Only takes a few seconds and one post.

Background

• This is necessary if want to install 1.73.8-1.75.1 or 1.80.1+ with its new partition structure. See also here: WARNING: 1.73.7, 1.73.8-1.75.1 and 1.80.1+ flash partitions are different!

• Any modded 1.73.8+ with 1.73.7 or 1.80.1+ with 1.73.7/1.75.1 partition structure is a mod, it will not upgrade future new partition structure firmware released by XYAUTO/XYGALA.

• 1.73.8+ running with 1.73.8+ partition structure is noticeably faster than 1.73.7.

• Relatively safe and even safer if make a TWRP backup before flashing firmware.

• Once learned how to flash firmware, can recovery from any bricking.

• Format flash will erase app activation codes. Read here for ZLINK/X-Car and here for 360 camera.

• This is also how to recover an HU if it's bricked. Note there are also other brick recovery tools such as TWRP and even simpler wrong Display Driver recoveries.

• Most of the steps can be done at your desk away from the car. Only need to connect to HU when flash tool is fully configured and ready to flash.

Flashing firmware via PC

1. Do Simple Backup ( link ) In case of wrong firmware (e.g. wrong display driver) it may very hard to get it working again without correct firmware. In the past 1280x720 HUs got bricked several times by wrong display drivers and needed to be recovered. Especially make a backup when your HU has not 1024x600 display resolution.

2. Make sure you have everything from Tools needed for PC flashing or brick recovery section.

3. Download firmware, you need both OTA and the PC package file. OTA file is only needed for the preloader file. Since 1.80.1 OTA files don't have preloaders anymore included, you need to take the ones from 1.75.1 (see here). They are also archived at "Missing files" archive.
   For getting the correct firmware for your HU, read everything here: Firmware.

4. Extract PC firmware file.
   IMPORTANT : Remove all Chinese characters from downloaded .zip files or rename extracting folder. SP Flash Tool will fail with these characters in the path name.
   From now on the folder with extracted PC firmware is called "PC Pkg" and the folder with extracted OTA firmware is called "OTA Pkg".

5. Extract and launch SP Flash Tool (flash_tool.exe; admin privileges don't hurt). It will complain that there is no scatter file. Just okay it and get it launched.

6. Choose the file "MTK_AllInOne_DA.bin" in the same folder as SP Flash Tool for "Download-Agent".

7. For "Scatter-loading file", choose "AC8257_Android_scatter.txt" from PC Pkg unzipped folder. This will populate most rows except "preloader".

8. Choose the" preloader" from OTA unzipped folder. For 1, 2, 4 GB RAM HUs, choose preloader_Xg.bin (X=1, 2, 4). For 6, 8 GB RAM HUs, just choose preloader.bin. preloader line will populate fully (including End Address) and box checked.
   Note: 1.80.1 no longer includes preloader files in OTA files. You need to get them from 1.75.1 or "Missing files" archive section.

9. Depending on you HU several files will be missing (lines with no checked boxes):
   For 2/4GB YT5760B 1.73.8: no other missing files.
   For 6/8GB YT5760B 1.73.8 horizontal: metazone and logo are missing.
   For 6/8GB YT5760B 1.73.8 1024x768 vertical: metazone is missing.
   Get logo and metazone from step 1's Simple Backup effort, place them into extracted firmware folder and choose them in SP Flash Tool. You can get preloader and logo from or "Missing files" section.

10. Ensure that there are no Chinese characters from downloaded .zip files.  SP Flash Tool will fail with these characters in the path name (files or folders).

11. When all the scatter files are populated, select "Format All + Download" in drop down list:

13. After selecting "Format All + Download" in drop down list, click "Download" button. This will trigger SP Flash Tool to check everything is okay and wait for the USB connection to begin flashing firmware. Your HU should not be connected to your PC at this point
WARNING: Do not use the "Format" tab in SP Flash Tool, only use "Download" tab. "Download" tab includes an option to format before download firmware. Format tab includes an option to erase bootloader. I don't know what problems will encounter by using this.
Last Reminder: Full format will erase all local activation codes and calibration data for apps.

14. Connect your HU to PC via USB cable. On the 5760B, only the 6pin USB port works to connect to PC for flashing and brick recovery. Some older thread for older HUs says 4pin USB, but not true for this HU. If you don't know which is the 4pin USB port and which one is the 6pin USB port, try all ports. Don't worry if you've plugged into the 4pin USB port during recovery, because it won't connect.

15. Plug-in your HU into power or if already powered on, press "RST" (there is a small hole with a button inside).

16. Now you should hear a Windows USB connection sound and the flash process should begin a few seconds later. Flashing process will take about 2 minutes.

17. Backup and PC flash require pressing RST button multiple times. If doing this at night without excellent surround lighting. Be careful as MIC hole is just above RST in some HUs. ( post #3802 )

18. After finish, disconnect USB, press "RST" and HU boots new firmware. It will take a few minutes until the HU finished booting. Android animation logo takes a long time (several minutes). Probably Android has to unpack and populate its files. After UI comes up, Android seems to be still doing some unpacking adding/deleting apps and you'll see a "finishing system update" notification on the upper left corner link. Just wait until it has finished.

19. 360 camera may appear to ask for activation. Backup camera is set to 360 camera by default. You need to go change it in Factory Settings.
ZLINK/X-Car should activate after getting internet access. See also here.
HU will eventually popup window complaining about no IMEI. See here how to repatch IMEI.

20. See here for several other UI issues after flashing: UI issues after firmware flashing via PC.

21. Please read this section: Helping the community

Here is a video of the flashing process:

Source: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88215923

Missing files archive

Preloader, metazone and logo are often missing in *hw* firmware files for PC flashing:

• Preloaders have never changed so can use the archived version in the repository.

• There are 3 different preloader files.  Make sure you use the correct one, wrong one will brick the HU.
  "preloader_2g.bin" is for 2GB RAM versions
  "preloader_4g.bin" is for 4GB RAM versions
  "preloader.bin" is for 6/8GB RAM versions

• Metazone and logo.mrf is best extracted from the HU if it's running ( Simple Backup )

If planning to do PC flash, do Simple Backup noted above incase bricking the HU. If bricked, see if it is wrong display driver and follow  wrong display driver recovery.

preloaders are archived and listed here:

Flash Failures

Here are some encountered failures while flashing

• Firmware files stored on simple USB Pen Drive ( post #4708 )

• HU has bad USB ports with daughter cards ( post #4685 #4689 )

IMEI repatch

NOTE : Before restoring IMEI, it is assumed, that HU's flash memory is not blank. A firmware has been loaded and it's maybe necessary to boot once even if Android complains about lack IMEI. I'm guessing firmware installation and Android unpacking the operating system likely creates the AP_DB necessary for patching in the following steps.

Read here if don't have IMEI

There are 2 tools for repatching IMEI. Download and install/extract "SN Write Tool" or "Maui Meta"/"Modem Meta":
- "SN Write Tool" can be downloaded from here and here. Only version 1.1924.00 has been successfully tested, version 1.2020.00 seems to fail.
- "Maui Meta"/"Modem Meta" can be downloaded from here or here. Only version 10.1816.0.01 has been tested.
Now go ahead with the method you prefer.

SN Write Tool method:

1. Make sure you have everything from Tools needed for PC flashing or brick recovery section, except SP Flash Tool.

2. Start car in case there is HU power shutdown timeouts in accessory mode -> HU will be powered on.

3. Launch SN Write Tool with admin privileges (not sure if they are necessary).

4. Click "System Config".

5. If there are 2 IMEI check "Dual IMEI" and if they are duplicated, also check "DualIMEI Same".

6. Check Load AP DB from DUT and Load Modem DB from DUT:
   - Click MD1_DB button and choose the APDB file ending in ENUM from the installed firmware's unzipped folder
   - Click AP_DB button and choose the APDB file NOT ending in ENUM from the installed firmware's unzipped folder

7. Click "Save".

8. Click "Start".

9. Enter IMEI (all 15 digits including checksum) into popup window.

10. Click OK. Now the SN Writer is searching for preloader com port and handshake.

11. Connect HU to PC via USB.

12. Press "RST" on HU.

13. Now you should hear a Windows USB connection sound.

14. HU will show boot screen with "=> META MODE" on lower left corner.

15. After successful IMEI write, SN Write Tool will show "PASS".

16. Remove USB cable.

17. After HU reboots, check Android "Settings" -> "System" -> "About Car" for your loaded IMEI.

Video of the steps above:

Maui Meta/Modem Meta method:

1. Make sure you have everything from Tools needed for PC flashing or brick recovery section, except SP Flash Tool.

2. Start car in case there is HU power shutdown timeouts in accessory mode -> HU will be powered on.

3. Launch Maui Meta/Modem Meta with admin privileges (not sure if they are necessary).

4. Click "Connect" button on lower right.

5. Connect HU to PC via USB.

6. Press "RST" on HU.

7. Now you should hear a Windows USB connection sound.

8. HU will show boot screen with => META MODE on lower left corner.

9. Maui Meta will make connection progress. Connected after reaching 100%.
   I had 2x failures where connection progress became stuck at 22%. Just click stop, close Maui Meta/Modem Meta and restart this launch and connection sequence.

10. Click "Load DB" and choose target. This will load the AP_DB info from HU. As long as HU flash has firmware installed (and maybe need to be booted at least once?), there is a valid DB in the target. Many threads talk about searching for DB files online. Completely unnecessary.

11. Chose IMEI download function on Search Tools box on upper right (click in box, all functions will display).

12. Click SIM 1 box, paste 14 digit. Click SIM 2 box and Maui Meta will compute checksum for IMEI 1

13. Click SIM 2 box, paste 14 digit. Click SIM1 1 box and Maui Meta will compute checksum for IMEI 2

14. SIM box interface is error prone. It's necessary to click the other SIM box to have an IMEI properly loaded into software (and shows computed checksum). After entering both, I just click both box alternatively a few times to be sure.

15. Click "Write" and wait for success message. Can run IMEI download function again and click Read to confirm.

16. Click "Disconnect" and remove USB cable.

17. After HU reboots, check Android "Settings" -> "System" -> "About Car" for your loaded IMEI.

Video of the steps above:

IMEI RePatch Failures

PC too old ( post #4628 )

Sources: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88206723
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88215621

Failures

Have heard of following failures in IMEI repatch.

• Resolved by removing HU and use 12V battery ( post #1996 )

• Resolved by 1.80.1 rather than 1.73.8 ( post #4068 )

• PC too old ( post #4628 )

Review prior posts from poster to see their IMEI repatch problems.

OTA install via TWRP

1. Flash TWRP.

2. Put OTA firmware file onto FAT32 or exFAT formatted USB stick. Preferably an OTA with same partition structure as one that failed. Easiest is just to use same firmware version.

3. Boot into TWRP typing in "reboot recovery" in terminal app and press return.

4. Choose "Install".

5. "Select Storage" to USB stick.

6. Choose OTA file.

7. Swipe to confirm flash.

8. After flashing is finished, reboot system.

Caution: Flashing OTA firmware will also erase TWRP recovery and replace it with XYAUTO recovery. XYAUTO recovery allows "Car Settings" -> "System Info" -> "Android Upgrade" button to install other patches.

Source: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88206725

Flash TWRP

1. Make sure you have everything from Tools needed for PC flashing or brick recovery section.

2. Make a backup of your current firmware in case something went wrong and you soft brick your HU.

3. Download firmware/driver files you want to flash. Also download TWRP from here:
   https://mega.nz/folder/IKF2TaCb#s-YBPnEaIFR1VCCJTKlS2A

4. Extract TWRP files (recovery.img and vbmeta.img).

5. Put AC8257_Android_scatter.txt from your firmware (must be PC package firmware file) next to extracted TWRP files. There should be no other files in this folder.

6. Extract and launch flash_tool (admin privileges don't hurt). It will complain that there is no scatter file. Just okay it and get it launched.

7. Choose the file "MTK_AllInOne_DA.bin" in the same folder as SP Flash Tool for "Download-Agent".

8. Select "Download only" in drop down list.

9. For "Scatter-loading file", choose your "AC8257_Android_scatter.txt" placed in the TWRP files folder.
   This will populate the flash tool screen like this, only "recovery" and "vbmeta" should be checked, so only these 2 files will be flashed:

10. Click "Download" button. This will trigger SP Flash Tool to check everything is okay and wait for the USB connection to begin flashing firmware. Your HU should not be connected to your PC at this point
WARNING: Do not use the "Format" tab in SP Flash Tool, only use "Download" tab. "Download" tab includes an option to format before download firmware. Format tab includes an option to erase bootloader. I don't know what problems will encounter by using this.

11. Connect your HU to PC via USB cable. On the 5760B, only the 6pin USB port works to connect to PC for flashing and brick recovery. Some older thread for older HUs says 4pin USB, but not true for this HU. If you don't know which is the 4pin USB port and which one is the 6pin USB port, try all ports. Don't worry if you've plugged into the 4pin USB port during recovery, because it won't connect.

12. Plug-in your HU into power or if already powered on, press "RST" (there is a small hole with a button inside).

13. Now you should hear a Windows USB connection sound and the flash process should begin a few seconds later. Flashing process will take a few seconds.

14. After finish, disconnect USB, press "RST" and HU boots up. TWRP is the new recovery now.

15. To trigger TWRP, install a terminal emulator app and launch it (it doesn't matter which one, you only need a classic Linux terminal on your HU; e.g. you can use this one).

16. In terminal emulator app type in "reboot recovery" and press return. Sometimes it takes a few seconds until terminal is ready.

17. HU will reboot now into TWRP. Follow the instructions until the main screen. TWRP will automatically turn off the screen after a short time. You'll need to turn this off (under Settings). If goes blank, need to press "RST", boot HU, run Terminal with "reboot recovery" command to get back to TWRP.

Here is a video on TWRP installation (Note: It took a while for terminal emulator to show prompt. This seems to occur every time. Probably just need to let it sit for a while after firmware boots up):

Sources: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88206723
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88206725

Rooting HU with Magisk

1. Make a backup of your current firmware in case something went wrong and you soft brick your HU.

2. Copy "boot.img" from the flashed firmware .zip file to HU.

3. Install Magisk app on HU, version 22 is recommended.

4. Run Magisk app -> "Install" -> "Next"step -> "Select and Patch a file" -> select your "boot.img" and patch it.

5. Copy patched "boot.img" file back to PC into a new folder and put "AC8257_Android_scatter.txt" from your firmware (must be PC package firmware file) next to your patched and copied "boot.img". There should be no other files in this folder.

6. Install "MTK Driver" with admin privilege (not sure if necessary). Installation will ask if want to remove USB drivers. Click "Okay" (Its only removing previously installed Flash Tool drives, doesn't touch any other USB drivers). Let it finish and reboot Windows. I had to prompt the installation with return key a couple of times to get it to finish.

7. Extract and launch SP Flash Tool (flash_tool.exe; admin privileges don't hurt). It will complain that there is no scatter file. Just okay it and get it launched.

8. Choose the file "MTK_AllInOne_DA.bin" in the same folder as SP Flash Tool for "Download-Agent".

9. For "Scatter-loading file", choose "AC8257_Android_scatter.txt" from unzipped folder. This may populate only "boot" row.

10. Select "Download only" in drop down list.

11. Click "Download" button. This will trigger SP Flash Tool to check everything is okay and wait for the USB connection to begin flashing firmware. Your HU should not be connected to your PC at this point!

12. Connect your HU to PC via USB cable. On the 5760B, only the 6pin USB port works to connect to PC for flashing and brick recovery. Some older thread for older HUs says 4pin USB, but not true for this HU. If you don't know which is the 4pin USB port and which one is the 6pin USB port, try all ports. Don't worry if you've plugged into the 4pin USB port during recovery, because it won't connect.

13. Plug-in your HU into power or if already powered on, press "RST" (there is a small hole with a button inside).

14. Now you should hear a Windows USB connection sound and the flash process should begin a few seconds later. Flashing process will take about 2 minutes.

15. After finish, disconnect USB, press "RST" and HU boots up.

16. Go into Magisk app -> "Install" -> "Next" -> "Direct Install (Recommended)" (this is a new option now) -> "Let's go"

17. HU will be restarted and is rooted now. When starting Magisk, a message "Abnormal state" may appear. Ignore it.

Sources: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-84757223
https://4pda.to/forum/index.php?showtopic=1000527&st=160#entry99534170
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89687040

Fixing random bootloops after rooting with Magisk

Flash this patch:
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89339768

64bit firmware in <= 4GB HUs

https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88235163

My volume +/- touch zone shifted after this upgrade:
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88236363

UI issues after firmware flashing via PC

PC firmware flashing with formatting the whole flash memory is like re-manufacturing the HU. Some UI issues may occur and require calibration/adjustment (e.g. in "Factory Settings") which was probably done at the factory.

These issues seems to vary from all the different versions of this HU. Some have more and some less.

General strange behavior

There may be some strange behavior after first boot:
- No "Car Settings" app for a while
- "Car Settings" app crash after entering 8888 password in "Factory Settings"
- Steering wheel control doesn't work
Best to let it sit for few minute and reboot it a second time (or press "RST" if no "Car Settings" app)

X touch coordinates reversed

There are several solutions:

Pressing with 5 fingers and shaking brings up touch calibration tool and after following its steps it should work fine.
Sources: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88493787
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88089747

Go to "Car Settings" -> "Factory Settings" -> "Touch settings" -> "key position" -> "no key" instead of "swap left and right" which is the default setting.
Source: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89674847

Volume +/- icon touch doesn't work

The touch zones seems to have moved above the +/- icon. All other touch icons above them works fine (back, home, power).

Physical dial backwards

"Car Settings" -> "Factory Settings" -> "Encoder Settings" -> change "Encoder X setting" to "positive direction" or "negative direction".

Sources: https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-88494295
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89092117

Recalibration

See here: Touch screen and dial re-calibration.

Display image and touch inverted

https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89223937

https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89223947

Touch Positions Incorrect

I think the display resolution and touch resolution are potentially different on these HUs and can result in incorrect touch position if touch resolution is set same as display resolution. See post #4928 through #4932

Colors messed up

Maybe related to 6bit/8bit display difference. Can be toggled:
https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89223947

Another user experienced flashing firmware to vertical HU resulting in bad colors that eventually corrected itself after multiple reboots (see here, here and here at XDA).

No More CANBUS Connection

https://xdaforums.com/t/ac8259-cpu-based-hu-problems-questions-mainly-yt5760.4171219/post-89736859

Also see follow up post #3456