Make sure the cables are on correctly [IE red line pin 1 on all boards] and double check they and not reversed or off by a pin or a bent pin etc ............also check for power at the dmd and dmd controller board.

yup you can test any dmd in any game. With the power off swap them out and then power on.

And yes I know thats how you got into this mess but I have seen cables placed on backwards before and they do not do any damage they just read funny or garbled.
What are your power readings at the actual dmd? And you never know about the cables. Seen bent broken missing pins or kinked cables or off by a pin or backwards.etc etc and seeing how that was what was last touched its always worth checking again.
I suspect bad power to your dmd or bad dmd controller board. There is static chips that can go by touching them if you were not grounded before touching the board.

You are welcome ...but ...what was it?

Also is your dmd connected by little pins or is it a large ribbon strip connection? VERY common for the little pin type to break where they enter the glass. but do not mess with it unless you are confident in your repair skills as you can easily make it worse because the other pins are not far behind. If its the ribbon type I have seen the strip edge peel away and just a little press and hold was all it took to fix it. AGAIN... better to let sleeping dogs lie here unless you are getting/have a new one.
There are some things to try if you are brave...range from soldering it to adding a conductive paste epoxy. Either way sees a moderate rate of success.