1. First of all, power the device off.
2. Now, hold down the Volume Up key .
3. As you hold the Volume Up button down, press and hold the Power key for 3 seconds, then release it. Keep holding the Volume Up button!!1!
4. When the tablet screen turns on, stop holding the buttons
5. By now, you should be in the desired mode.
6. Navigate the menu by using the Volume buttons and confirm options by holding the Power key.