Try starting it up in "Safe Mode" and see if it will load. If it does you will have limited access, but that will also tell you that there is something on the tablet that is causing your issue. Bad app, virus, malware, etc. which you would have to remove before you can run the tablet normally.
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.