Have you tried this?
There are a few things you should try first when you experience problems with your device:
Remove the cover for the memory card and nano SIM card. Then, using the tip of a pen or a similar object, press and hold down the OFF button until the device shuts down. After the device is turned off, restart your device.
Update your device to ensure that you have optimal performance and the latest enhancements. read more about how to update and find latest software version.
Reset your device to its original settings to free up memory: Settings > Backup & reset > Factory data reset > Reset tablet. Don't forget to back up any important data saved on your device!