Try this...
1. First you need to turn it completely off. Technically it is actually on, but not functioning correctly.
2. Press the "Power" and the "Volume Up" buttons, together, until you see the start-up logo on the screen.
3. Once you can see the logo, release the buttons and allow the device to enter the "System Recovery Mode".
4. Next use "Volume Down" button to get to the "wipe cache partition" option. When in recovery mode the "Volume Up" and "Volume Down" buttons are how to can navigate and highlight what option you need.
5. Once that is highlighted, press the "Power" button to select it.
6. Now while it is still saying "Wiping Cache", again hold down the "Power" and the "Volume Up" buttons, together.
7. Once you feel it...