htc one m9, won't turn on, black screen

[AC Question]

Was playing a game when it shut down, won't even charge- any idea where exactly the problem will lie internally please?

 

[B. Diddy]

Welcome to Android Central! Try pressing and holding Power for 15-20 seconds, which might force a power on. Conversely, it might also force a shutdown, if the phone is actually frozen in an on state, but just with the screen blank. So after pressing it the first time, wait a few seconds then press and hold again for another 15-20 seconds.