Try starting it up in "Safe Mode" and see if it will load. If it does, you will have limited access, but then you know there is something on the device that is interfering. Bad app, malware, virus, etc., which would have to be removed before you can access the tablet normally. Now if it won't load even in "Safe Mode" then you will probably need either a "Hard Reset", which will completely wipe the device and reinstall the original OS, or there is hardware damage and it needs to be looked at by a 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.