Thank you for the correction about the pins, of course you are completely right!
Also thanks for the tips with the core module. I will have a look at it, see if I can find anything obviously broken or determine better where the heat comes from and maybe check the capacitors for shorts as suggested here: FP2 dead - red light on constantly?
Next steps would be to try to get a broken phone to exchange the module or take the phone to a repair shop, whatever I manage earlier. I will post my progress.