Tablet displays "100" battery icon but will not actually boot

Hmmm… sounds familiar to a problem I had with my Samsung Galaxy S4 phone, and the issue was that the micro power button had broken away from the motherboard, so the device still worked normally, but I couldn’t power it on or go into recovery mode. I don’t know one hundred percent if this is the same problem you’re having, but if you are able to take apart your tablet remote, inspect the power button its self. see if there are any breakages in solder or if its a ribbon cable, see if it’s ripped anywhere. but if the power button is still showing signs of working, you may have a more deep-seated problem on your hands. hope this was helpful!