The voltage is most likely too low, on your main battery, and the charger insufficient. I've had the same problem with the samsung galaxy tab 7. try using the original charger first. if this option is not available, then find a High-amp wall charger, or High-power port on a computer. you should notice the battery screen that shows charge info while the device is off, will stay on a bit longer, to show the device is charging. if these option do not work, you might try a new charging cable. (my children yank the wires when removing the charging cable) this disconnects some of the delicate strands of wire within the chord, and reduces the amps available to the device. If all these things do not work, and only if all these things do not work, I have one more solution:
Warning, the following is a last ditch effort, and could cause damage to your battery.
Each AA battery is actually a 1.3 or 1.5 volt cell depending on it's chemistry.
Using a battery holder, cut the wires to a charging cable, find the colors, and polarity of the power wires, by using a volt meter on the usb port side of the cut cable. then attach the wires to the battery pack holder of batteries, four in series. if the strands are intact enouph to provide the current needed to jump start the battery, then this will work. do not use this method for more than 5 minutes, do so when the unit is cool, and after this treatment, the regular charging devices should work just fine, even the low power ones. don't bother trying to turn it on till you get it charged to at least 25 percent, otherwise you might have to do this again.
Unfortunately, I have done this many times on the the kid's tablets.