Ursprünglicher Beitrag von: mischakuh ,
Sounds like a Mainboard issue. Have you done something to the phone, like water damage or dropped it? There must be a main power supply for both, You need to open it and check with a multimeter (if you use it wrong you can destroy your device, or make it worse) can aso be a short to ground. A defekt switch (mosfet) and so on.