This happened to me last week. After about 20 drops @ 3-4 feet over the years, it started when I dropped it 2 inches on the table at dinner. Here is what I did to fix it.
1. Remove the battery
2. Remove the four rubber feet on the back side (use a toothpick)
3. Remove the four screws
4. Carefully open and close the ribbon cable sockets shown with red arrows in the picture. Use one or two toothpicks and move the pieces indicated with yellow arrows. Move it in the direction of the yellow arrows. Then move (snap) it back.
Put everything back and you should be good to go!
BeachTech
