Thanks for the additional info! I think we can set this right by performing a factory reset on the device. These steps should do it:
1. Make sure it's powered off, and the battery is fully charged.
2. Press and hold the VOL + button and the POWER button simultaneously, until you see the splash screen.
3. Release both buttons.
4. A new screen will appear asking you to use your VOL +/- buttons to move and the POWER button to select.
5. Use the VOL - button to highlight "wipe data/factory reset." Once highlighted, select using the POWER button.
6. A new screen will appear asking you to confirm your selection. Use your VOL - button to highlight "Yes -- delete all user data" then press the POWER button to select.
7. Once the tablet is finished wiping data, you may press the power button to select "reboot system now." This will restart your tablet.
Try that, and let me know how it goes! Oh, and please remember to rate the service I've provided. I hope it has been excellent!