Before trying to reset it you may want to try turning it on in "Safe Mode" and see if it will load. This way no personal data is lost. If it does, then there is something on the tablet that is the problem and needs to be removed. Virus, Malware, bad app, etc.
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.