Power off or restart your Android device
1) Press down and hold the power and side button. Hold until the image in Step 2 is shown.
2) For power off, tap Power Off.
For restart, tap Restart.
Factory reset your Android device
For the latest and most accurate information regarding how to power on your Android device, restart it, or power it down completely, please visit Google's support website at https://support.google.com/android/answer/6088915.