Try launching the tablet in "Safe Mode". If it will load in that, then there is something on the tablet, that was downloaded to it, that is causing your problems. You would have to remove that app/file and then restart the tablet to take it out of "Safe Mode". Should this not work, then I would contact the place you bought it from and have them get you a new working tablet.
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.