1. First, power the device off.
2. Second, hold down the Volume Up key for a while.
3. While you do that, press and hold the Power key for 3 seconds then release it. Continue holding the Volume Up button.
4. When the tablet screen turns on, stop holding the buttons
5. Good work! You should be in the desired mode.
6. Navigate the mode by using the Volume buttons and confirm options by holding the Power key.