Try starting it up in "Safe Mode" and see if it will stay on. While that mode will have limited access, if it stays on, that means you have something on the device that is the problem. Malware, virus, etc. which you would then have to remove to get the device workign properly again.
If, however, it won't even start up in "Safe Mode", then it could be a hardware issue. If under warranty, I would contact the manufacturer. If not, try a local tech.
To get into "Safe Mode" please do the following.
1. First turn off the tablet.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or something similar.
4. If you wanted disable it, simply repeat the steps above, and you should see "Safe Mode: OFF" rather than on.