Sounds like you have some software or app on it that is messing with your device.
The first thing I would try is to get into "Safe Mode" and see if the tablet will fully load then. If it does then you definitely have something on there you need to remove. I suggest starting with apps recently updated or installed, as well as any other recent things (music, videos, files, etc.) added to the device.
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.