Try starting it up in "Safe Mode". If it will load fully, you will have limited access, but you will also know that something is on the device that is causing it not to load normally. So you will have to remove that, be it a bad app, virus, malware, etc., then restart it.
Should it not start up in "Safe Mode" and still get stuck on the logo, then you may need to do a "Hard Reset" of the device. But I would save that for a last resort as it will wipe all personal data off 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.