There are a few things you could try to restore the functionality of your tablet.
Power off the device, then press Volume Up + Power until it enters the Recovery mode. Once in the Recovery mode, select Wipe data/Factory Reset. This operation will re-install the operating system automatically.
The tablet should have a Reset whole where you need to press the button inside with something sharp. After it's pressed, the tablet should start the recovery process.
If nothing above works, you will have to send the tablet to warranty or visit a local phone service shop. They should have the tools needed to bring the tablet back to its functional state.