1. Shut down completely first, and press and hold the power button for a second or two at the same time. Before the screen lights up, quickly press and hold the volume up and down, and then press and hold three buttons to enter the recovery.

2. Select Erase Data/Restore Factory Settings, then press the power button to confirm, and then select Yes-delete all data.

3. Select to erase the cache partition, then press the power key to confirm, and then select Yes-to erase the cache.

4. Then reselect to restart the system now, press the power button to confirm and start the mobile phone.