I have checked the connections a couple of times and they seem good.

Today the thing almost worked. The lights died down and then for a few moments the screen seemed normal with 72 degrees on both sides but still only the fan speed buttons working so I adjusted the speed down to zero and off and tried to restart the system and got only the disco light from then on.

Ordered a remanufactured controller from Mercedes. Will give that a try tomorrow. They will allow return if its not the problem.