There could be a few things. Try starting the tablet in "Safe Mode". If it lets the tablet load, then there is probably an app, or update to an app, that is giving you problems.
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.
If it won't load, even in "Safe Mode" then you may want to try a "Factory Reset". It 'may' remove some data that you have...