I had the same problem. The issue is that the cable for the battery is too short, and they left too much extra space around the battery housing opposite the cable. Thus, when the battery shifts away from the direction of the cable, the connection becomes loose, or disconnects entirely. If you pop that sucker open, connect the battery cable to the motherboard securely, and put a piece of cardboard (or whatever you feel works) between the battery and the outside edge of the housing; it will prevent the battery from shifting around the housing and keep the problem from happening again.
After I did this fix, the tablet was running better and faster than when I got it new. I attribute this to a loose cable when it was new, which probably forced the system to run at a lower voltage.