Samsung Galaxy S5 Problems booting up

[AC Question]

Hey guys, I need help with the following. My phone doesnt turn on anymore, if it does it will shut down after a second or two. I've been to the local repair guy, he said it might be the hardware keys that whenever the power button is pressed it sinks in and it doesnt let go. This doesnt happen though but I wondered if this might be true. So the phone only turns on for a second or two and shuts off. If I press the power button nothing happens, unless I put it on charge and then press it then only a green line appears for a splitsecond and nothing. Thanks in advance.

 

[belodion]

It may be not so much the button, as the switch beneath it. But a remote diagnosis is hardly possible.