Holding power, vol up, and vol down button for 10 seconds is a hard power off just like if you were to take out the battery. You can do this when the phone is doing anything like bootlooping, in recovery, on, etc.
If it does not work for you, then the power button is faulty.
Do this to turn your phone off. Then vol up + power to boot directly into recovery. Problem solved.
Sent from my HTC6525LVW using xda app-developers app