Learn how to do Hard Reset on your HTC One M8. If you cant turn HTC One on or access settings, you can still perform a factory reset by using the hardware buttons on HTC One.
Note
The Fast boot option in Settings > Power must not be selected.
- Press and hold the VOLUME DOWN button, and then press and hold the POWER button.
- Wait for the screen with the three Android images to appear, and then release the POWER and VOLUME DOWN buttons.
- Press VOLUME DOWN to select FACTORY RESET, and then press the POWER button.