1. Turn the device off completely, remove the battery
2. With the device turned off, press and hold the Volume down key.
3. With the Volume down key held down, press and hold the Power key.
4. Release the Power key when the Android system recovery screen appears.
5. Use the Volume down key to scroll to wipe data/factory reset.
6. With wipe data/factory reset highlighted, press the Power key
Press the Volume down key to scroll to Yes -- delete all user data.
7. With Yes -- delete all user data Highlighted, press the Power key.
8. Once the wipe is complete, with reboot system now highlighted, press the Power key.
The device will restart.