You may be experiencing any of these issues:

• Your phone does not boot to the home screen after powering the device on
• Your phone displays a red triangle with an exclamation point ! in the center
• Your phone is stuck on the HTC or carrier splash screens during the boot sequence

To reboot using the hardware buttons, hold down each of these button combinations for up to 2 minutes or until the phone powers on:

1. Hold down the VOLUME UP, VOLUME DOWN, and POWER buttons at the same time.
   
2. Hold down the VOLUME UP and POWER buttons at the same time.
3. Hold down the VOLUME DOWN and POWER buttons at the same time.
   On some phones, some of these combinations may power the phone on into the Bootloader or Download Mode screen. If a list of options appears, use the VOLUME buttons to scroll to REBOOT or Fastboot > Reboot, and press the POWER button to select it.

To avoid voiding your warranty or damaging your phone's system software, make sure you do not select the other options on the screen.