phone does not power on topic

My HTC One does not power on if it is shut down. When i have luck (which i had actually) the phone powers on. So now my phone is on - if i shut it off, it would not power on again. If it is powered off and i charge it, not even the led lights up. Is seems comletely dead.
I am now running the stock rom and stock recovery. But the bootloader is unlocked and it is s-off.. (no warrenty)

Does anyone have a idea to solve the problem? Or is there anyone with the same problem?


THX :)