HTC One M8 stuck on boot screen can't close it?

[AC Question]

HTC One M8 stuck on boot screen can't close it

Problem:
HTC One M8 Stuck on bootscreen, and I can't even close my phone. I've tried to get into the hard reset screen but it does not work (As I can't turn my phone off)

Details: Stuck about an hour ago when I tried to restart my phone. I have not downloaded any third party applications before, and the only thing I have downloaded within the past week was Pokemon Go.

What should I do?

Thanks in advance!