I would say best bet would be to pull it out, and see if it connected or not. Hopefully it is just a loose connection, and voila you're good.
If it is connected and still not working, then the screen has blown out and a replacement would be needed. I have not seen the screen on itself being sold, so you would have to purchase the entire unit.
I would say it is the best time to upgrade to the MKIV unit with the 16:9 screen.