the btphone_p3phm-v20231201-1 is the firmware not compatible with the previous versions. it has a little different way to update the firmware. and it always requires the USB recovery way from any older firmware than v20231201-1.
i have to create the new documentation. and i hope that i finish it this weekend or the next one.
so i would like to recommend that you wait a while. you save an extra disassembly.

finally after a quite long time the new version of the firmware is here. but this time it is the new from the scratch (same as P2 version, that you can find on the another thread).

v20240121-1 - documentation and firmware

the change is so huge that the update from the older versions is not possible to do with the standard way but it has to be done by USB recovery, see the documentation.

any inconsistencies please write here so I can learn and others don't have to struggle with it.

v20240303-1 - documentation and firmware

sometimes it has caused that the MOST has "frozen" (MOST extension) if engine was not started directly (the ignition on and then start the engine) and the battery was not fully charged.