To turn the phone on, press and hold the Power/Lock button until the screen lights up. Note: If you are unable to turn your phone on, plug the phone into a power source for 15 minutes, then try again.
To turn the phone off, press and hold the Power/Lock button.
Tap Power off.
Tap Power off.
If you are unable to turn your device off, press and hold the Volume down and Power/Lock buttons simultaneously for 10-20 seconds to force reboot the device. Note: This performs a simulated battery disconnect.
If you are unable to turn your device off with the Power/Lock button, take off the back cover, and then remove and re-insert the battery.