Many none 5760B HUs inquire information on updates. Here are some general information
5760B seems to have most info and firmware availability. Everything else seems to have much less. Firmware updates can easily brick the HU. Study how to do backup ( MediaTek platform backups here ) on your HU if want to go ahead and attempt updates. Spend time and look into fully backing up firmware if info and firmware availability is rare.
This website can provide general set of understanding require in attempt firmware patch or full updates. Most of the tabs are top are probably relavent and similar in some way to none 5760B HUs. Much reading is required to get an understanding of the risks before jumping into patching or fully upgrading firmware.
HUs running xyauto firmware have some availability as xyauto released firmware updates via online file server. Server keep on changing. However, the community keeps gaining access :)
This website archived 5750B 7260B 7260L 7250B 7360B firmware but much less famiiarity than 5760B. These HUs are highly similar to 5760B but its unclear of exact compatibility and therefore organized information. Here is the search on the xdaforum post for 7260B ( link )
Some xyauto firmware links can be found here
Again, there are very little info on these thus the high bricking risk. So study backups mentioned earlier.
none xyauto firmware HUs nearly generally have no firmware access. Some owners receive files from seller and post online. This is often without complete background info or any structure. HU brick chances can be very high.
There are few key terms to find and use google to find forum thread discussions with the same HU. These include
Vendor name
HU model ID and model number
Board model number
Android os build string
Read these sections ( link ) for more info