Soft reboot the device if you can... It should be by holding the power button and volume down button for over 5 seconds - or until it reboots. It might just be a bug that needs flushing out. Or it could have been an error in the OTA download and subsequent install. If restarting the device doesn't help, or it fails to restart... Take it to Samsung, they'll likely to a factory reset and do fresh, wired installation update. But at least then, it'll be fixed.
