I had the same problem - Touch screen was also not working. Fortunately, I've played with these tables a lot. Pop the case open, undo all the connectors and re-seat the connectors.
To open the case, use an exacto-knife, but don't use the point of the blade! use the long sharp blade layed flat and place it at the middle of the seam between the 2 edges (start at the longest side first). Once the blade is placed in the seam (where the back case meets the front screen - just above the actual screen), then rotate the knife so the case opens. Stick your fingernail in the opening (and leave it there) and move the knife up 1 inch and repeat - walking around the entire screen.
Once it's open, don't pull the front & back halves too far apart (the wires for the speaker connect the 2 halves). Turn the front (with the screen) over and you'll see amber cables that fit into white sockets. On the white socket there is a gray bar. On some of these connectors, the gray bar rotates up to release the cable, on others they pull out (towards the cable). Don't pull to hard on these gray bars, just go slow and be patient. Once the gray bar is rotated/moved back (they are always attached, so don't try to pull them all the way off), then pull the amber cables out. I like to clean the contacts with rubbing alcohol, but usually just reseating them does the trick. Then put the gray bars back to their original position.
When re-assembling the case, don't pinch wires, and check the power/volume buttons (I usually point the part of the case that has the buttons down, so gravity will hold those plastic pieces in). Push the front/back haves together walking around the entire case (you'll hear a click when those plastic tabs catch).
As to firmware - I'm still looking for prototec's firmware selection too!