1. When the phone is turned off, press and hold the power button and the side volume button at the same time to turn it on.

2. Press and hold the side volume button for about 15 seconds, until the Android icon is displayed on the phone screen, and the phone enters recovery mode.

3. Click the lower right corner of the phone screen to display menu options.

4. Press the side volume button to display "Erase data/restore factory settings" in reverse color, and then click OK in the lower left corner of the screen to confirm.

Press the side volume button on the screen to display "Yes-delete all user data" in reverse color, and then click OK at the bottom of the screen to clear all user data stored on the mobile phone.

5. Press the side volume button to display "wipecache partition" in reverse color, and then click OK in the lower left corner of the screen to clear the cache partition in the mobile phone.

6. Press the side volume button to highlight "Restart the system now", and then click OK in the lower left corner of the screen to restart the mobile phone system.