Have you checked to see if any of the buttons are stuck? Check for dust, food, etc. Happens a lot.
And is this what you did to try and reset it..... which is a "Hard Reset" and removes your data, so it is only recommended as a last resort....
AGAIN PLEASE NOTE: Doing this will clear the data on your tablet, so it is suggested you not choose this option unless you have to, or aren't worried about losing anything on the tablet.
To "Hard Reset" the tablet...
1. Make sure that the tablet is actually powered off.
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...