Well, you don't want to do that "Hard Reset" just yet. As it will erase everything on the tablet. First try and see if the device will start up in "Safe Mode". If it will, then you have something (virus, malware, bad app, etc.,) on it that needs to be removed/cleaned up. Once that is done you can then restart the tablet to get out of "Safe Mode".
To get into "Safe Mode" please do the following.
1. First turn off the tablet. (Let the battery drain down if it won't turn off by pressing the button. Then plug it in to charge, but do not turn it back on, yet.)
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...