Heater fan intermittent, now stopped?

Nissan Almera 2005, with A/C but never worked. It has been idle for several months but starts easily.

Had the car three and half years, never a problem with the heating/demist function.
heater/demister fan started dropping to a lower speed then cutting back to full. Removed glove compartment and jiggled connections.

There was some response when the lower connection to the many pin'd plugs on the left were moved, but only the once. Further jiggling caused no response, the fan continued to work. Sat there with engine running looking at Hyenas, then fan speed on max was OK, but dropped to a lower speed, then increased without anything being touched.

Then it all stopped. No fan action at all.

Removed fan motor and filter housing, removed plugs and heavy aluminium based electronic gadget thing (mounted vertically on the left), looked into the circuit board box mounted beneath the motor with chips - not touching that! - replaced all, reconnected, no joy.

I can hear the servos working flaps dependent on 'mode' for screen or car, but fan dead. Only looked at fuses under the bonnet so far. Am I missing something obvious (quite possible).