HW Install
General Hardware Installation
Mine came with all adapters for gen3 Prius from aliexpress seller. Plug and play.
Didn't come with mounting brackets into existing HU chassis mount location. Used metal pipe hanging straps cut to length and bent to shape for mounting. Used 4 holes on HU side to mount. Avoid using deep screws (ones from my original HU was deep enough to contact capacitor and cellular antenna post, use washers to reduce depth) See here
https://forum.xda-developers.com/t/ac8257-cpu-based-units-problems-questions-couldnt-find-any-info-about-it.4171219/post-86152977
Steering Wheel Controls and CANBUS Installation
Generally, there are 2 options
Without CANBUS
If original car radio doesn't have CANBUS interface, then steering wheel controls is through the KEY-1 and KEY-2 signals on the main power connector to this HU.
Without CANBUS box, other car data is not available. For example, steering wheel angle (to curve the backup camera guide lines). Climate control info and others.
With CANBUS
Some original radios include CANBUS interface signals. This requires having a CANBUS decoder and the matching main wiring harness to connect to this HU (HU does not have CANBUS decoder built-in)
Rear Camera Installation
Typical installation is as follows
Camera usually powered by backup light. Connect to backup light power source
Video cable include additional internal line indicating backup camera is powered on. (thats why video cable has red wire connection on each end). One end connects to the backup light power (to signal backup camera is being powered on). The other end connect to HU's cable for detecting backup signal. See this video for reference
connect Reversing back up camera on Joying android 5.1.1 lollipop car head unit radio - YouTube
Need to set the video camera format correctly. Also see how to enter various menus on the HU below
https://forum.xda-developers.com/t/ac8257-cpu-based-units-problems-questions-couldnt-find-any-info-about-it.4171219/post-86222561
Removing HU
The most challenging issue is disconnecting the rear cam/wifi and 2x USB connectors. The connections are so tight and very few wires that its easy to rip out the wires from the female metal connectors. I ripped out both video wires (really thin wires) and pulled out USB wire enough that it no longer made contact. Both was repaired (USB connector pushed back in, video metal connectors removed from plastic connector and resoldered and pushed back in)
Probably need to use needle nose plier and a pick to carefully pull out these connectors.