Hi i also cant find schematic. Can you measure EN1 and EN2 signals in 3.3/5V converter? What is power consumption on laboratory power supply. Propably you are right about PCH. ON photo i see coil and 2 mosfets neer by PCH measure resistance coil to GND.
Posted after 1 hour 27 minutes 22 seconds:Do you know how to do the short-test which laboratory power supply?
If you can, you can remove coil in 3.3v and put voltage 3.3v, 500mA from laboratory power supply to coil pad if power compsumtion will be 500mA check PCH is he hot, if not pull up current 100mA untill you feel temperature on PCH. Then remove PCH and do another shortcut test.
There is some information how to do short-test on this forum.
https://www.elvikom.pl/szkolenie-nr-1-p ... -t986.html