I had this problem, and the only solution I could find was to hard reset the tablet back to original settings.
It helps if your tablet is completely charged before starting this process.
1. Make sure it's off. (If it's anything like mine was, you may have to press and hold the power button for about 10 seconds until the screen goes black, then connect power (either USB or power cord) until you see the battery charging image... then disconnect power and continue).
2. Press and hold the power button and the volume + button. (Again, about 10 seconds)
- When you see the "visual land" screen, you can let go of the buttons.
- Now you should see a picture of the android on its back with a front panel open, and an exclamation triangle.
3. Press power, and while holding power, press the volume + button again once and release both buttons.
- Now you should see "Android system recovery" text on the screen with instructions to follow.
4. Use the volume down/up buttons to navigate through the menu. If you've made a backup before, scroll down to that option, or you may have to "wipe data/factory reset".
(This is as far as I could go, since my volume down button is broken... but hopefully this will help you move forward.)