The behavior that you encounter could be encountered due to a hardware malfunction. If you can't overcome the problem after you performed a hard reset of the device, I strongly suggest that you take the device to a specialized service. To perform a hard-reset, turn the tablet OFF. To enter the recovery menu, you need to press the Recovery button. This is located on a side of the tablet inside a hole. To press it, you need to enter a pin in the hole. While the button is pressed, simultaneously press and hold the Power button until the Android logo appears on the screen. After you entered the recovery menu, select Wipe data / hard reset. If your tablet doesn't start after this, contact an official service.