To turn on, press and hold the Power/Lock key 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, and then try again.
To turn off, press and hold the Power/Lock key. Note: If you are unable to power your phone off or if it becomes unresponsive, press and hold the Power/Lock key for 10 seconds until it reboots.
Tap Power off. Note: If the screen immediately goes dark, you did not hold the Power/Lock key long enough. Unlock the phone, and then try again.