iPhone X BootLoop - NOT due to earpiece

Hi Everybody.

I’m looking for an answer, or a least to be pointed in the right direction.

I have an iPhone X lying around, that bootloops. I’ve tested the following:

Screen, earpiece, battery - start up without powerflex and volume/QI flex, unplugged back and front camera - basically a start up with just screen (without earpiece, also with replaced earpiece) and battery.

Normally this would be a way to start it up, however only with screen and no other functionality.

I’m thinking it’s a board issue - but the phone accepts resetting with MacOS and/or iTunes. - no errors, stabile connection and no bootloop, but when starting back up afterwards, it just continues to loop.

Can anybody help me? :)

Thanks in advance, have an awesome weekend!