Instruction I:


1. First, press'n'hold the Power button until a menu will appear.
2. Second, select the Power off option.

3. Wait for a few seconds and then press'n'hold the Power button until the phone turns back on. Done!

 

Instruction II:

 

1. Begin with some manual work. Carefully remove the device's back cover and battery.
2. Do nothing for five seconds and then put everything back in place. Press the Power button.