To turn the device off, press and hold the Power/lock button.
Tap Power off.
Tap OK.
To turn the device on, press and hold the Power/lock button until the screen lights up.
If you are unable to power your device off or if it becomes unresponsive, Press the Volume down and Power buttons at the same time for 7 seconds to reboot the device.
If you are unable to turn your device on, plug the device into a power source for 15 minutes, and then try again.