Lets first try a hard restart this can be done like this . https://www.youtube.com/watch?v=-4HyqLg7cO4 If this doesnt work try a factory reset, to do a factory reset do this https://www.youtube.com/watch?v=Y1TzS3oIVMY but remember if you do a factory reset you will return the tablet to the state it was when you bought it all your data pictures and loaded games will be lost.
One last thing you can do is disconnect the battery this guild will help you through the process
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