Try starting it up in "Safe Mode" and see if it will load. Now you won't have access to most apps (it is a restricted mode) however if it will load up fine in there, then you have something on the tablet that is the problem. Bad app, virus, malware, etc., that you will have to remove to fix the problem.
If, however, it still freezes and won't load correctly even in "Safe Mode", then you are likely looking at doing a full "Hard Reset" or it is a hardware issue.
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.