Press the power button and then select "power off" to turn it off. Then press and hold Power and Volume down buttons simultaneously. Five seconds later you will see LG logo displays, now you can release the keys. Press Power and Volume- buttons again until the Hard Reset menu appears. ...
Because there are many different Android devices, the steps described above may need some minor adjusting to work on your device. Remember that the goal is to verify that your device is automatically backing up data and settings to your Google account and then perform a factory reset to recover...