This will sound weird but try pausing the DVD, closing the screen and then pulling it back open after a few seconds. Hit play on the DVD after that and see what happens.
Ours has a similar issue but plays sounds, no video. We figured this trick out after playing around with the screen.
One thing I can say, removing the screen (and the infotainment screen) is quick and easy. If my pause trick doesn't help, check out the harness plugs. Each screen only really requires one screwdriver type to slide out and inspect.