Common fault is also the USB C daughter board and even the power button board.

If it charges but fails to turn on, power button board can be the culprit.
If it doesn't charge consistently (like it will only power on or charge if you remove power for some time and plug back in), it may be a sign the power in daughter board is bad.

If it powers on but doesn't display, pretty much usually the motherboard - but just press the caps lock key to make sure it's not posting - to be safe.