Battery will not charge
Make sure the AC charging adapter is actually putting out the correct voltage. You can get a cheap meter at places like Harbor Freight that will measure the voltage across the tip of the charging cable and the battery. If the tablet uses a USB cable for charging, try another USB cable and see if you get the same result for battery charging. IF you are already using the cable just to get power to run, it is probably the battery needing replacement. It is difficult to get these tablet cases open without the proper small tools. If the tablet is not under warranty, try taking it to a cell phone store - they usually have the tools to open these cases. Once you have the case open, look at the battery dimensions, voltage and maH capacity, usually on the battery label. Go to Ebay and try and find a replacement battery with the same size and voltage rating, preferably with a higher maH rating. Try searching for ProScan battery or by battery model number and you may get lucky finding a replacement.