You should reseat both ribbon cables that run from the MPU to the DMD controller board. Try running a display test in the game menus all the way to the end where it tests reads/writes from the MPU to the video RAM on the DMD controller board. The results may be hard to read but that will test if there's a data communication problem between the boards.
You can also try swapping the DMD controller board from another WPC game to see if the problem follows the DMD controller.