I just wanted to give an update.
I contacted Bogen, the US distributor of Metz, and they answered that they do not handle the Hasselblad modules and have no information.
So I contacted Hasselblad, and they said it was probably caused by the module being slid too far into the module socket on the controller. I see this has also been mentioned in this thread.
This sounds like a distinct possibility as I thought the Metz module design, and particularly this connection was pretty flimsy.
I have already sent my unit back to B&H as I didn't want to get stuck with a bad unit. But now that I think it is workable, I will re-order it and give a full report. Probably after the holidays.