I am trying to help someone. He is a first-time H'blad user. While he was turning rings and pushing buttons he ended up in this situation: With the lens on the camera body and the magazine off the advance knob will not turn. The mirror is up and the back doors are open. (I don't know if the shutter is open). The shutter ring is at B but it probably was rotated after this situation presented itself. How do we get the camera back to normal operation?