Series s on and goes off

hello I bought a series s here that has the problem after switching on that it switches off again. now i have disassembled it but found nothing 12v coming from the power pack. when i remove the ssd the console starts and stays on. could it be that the ssd is defective? If I connect it to the pc, I can access it normally. anyone maybe an idea would be very nice and helpful thank you greetings from germany