Sometimes updates don't work as they should, despite the heavy testing done on the Google's side. The one simple thing that you can do is to either reset the tablet to default mode or simply restart it in recovery and wipe the cache.
For most of the tablets, simply turn it off then press Volume Up + Power. While you are in the recovery mode, there are two choices:
- Wipe Data /Factory Reset: Restore the tablet to initial condition.
- Wipe Cache: Clears some files and sometimes various errors caused by updates and upgrades.
Note: If the tablet is still on warranty, send it to be serviced.