Switch off the device. Hold down the Volume Up key and the Power button. When the "Boot Mode" appears, release the keys and open...
Switch off the phone, then hold down the Volume Down key and the Power button. Next, choose "Clear eMMC" using the Volume keys and...
Switch off the phone. Press and hold the Volume Up key and the Power button. When the "Recovery Mode" appears, release the keys. Now...
Switch on the device and go to "Settings". Next, choose "Backup & Reset". Here click on "Factory data reset". Select...
Switch on the device and go to "Settings". In Settings go for "Language and input". Next, choose "Language". That's...
The phone must be on. Use Dialer to enter the proposed code: *983*22387#. Finally, choose "Yes". Great! Wait until the process is completed.