Firmware update difficulty

Help! I was trying to charge my battery on my LG Gpad 7.0 devices. Both devices were under 10% battery. When I plugged it in, it immediately flashed Firmware Update, telling me not to unplug until the update had finished. It read 910K B13 UNROOTED underneath. 7 hours later, the update was still at 0%. This happened on both devices. I then proceeded to unplug the devices and restart them to see if they had been charged, and to see if there was another way to go about downloading the update. It did not charge either device, and now my battery is too dead for either device to proceed with the update. I'm completely stuck. I've plugged it into the wall as well as the computer and neither way has worked. Every time I plug it in, the Firmware update comes back up. Help!