Quoted from Dmod:

That’s the right path for debugging. Since everything appeared to be connected properly at the time the photo was taken and menus on the display are working, there’s a problem with the video signal coming from the game to the ColorDMD.
It’s either at the output of the display board or input to the ColorDMD board.
To check the whitestar display board, need to revert back to the old display to see if it’s still working. If not, could be a problem with the display ROM chip or damage to the board itself.