BMW 3 Series convertible top repair. Specifically 2002-2006.
I talk about other top issue causes at the very end of the video.

Convertible top systems can be complex as they consist of hydraulics, electrical, computer module (cvm) and many sensors and sensor types. They all have to work together in a domino affect type of motion to operate. If one signal is interrupted during the motion, then the system will stop or go offline.
This video shows the easiest things to check before in depth diagnosis is needed by a professional.
I diagnosed this vehicle first using diagnostic software test plans.