[turboboy]

Just to follow this up, my son stripped the door card off and found that the module had melted, along with the plug/socket and damaged the wiring.

On ordering replacements from the local Volvo garage they said they had not heard of the module having caught fire before and suggested that the wiring at the door hinge had broken and caused an electrical spike or incorrect signal. Our feeling is that a failed module component caused overheating.

Upshot is that when the parts arrive and are fitted it will still need a software download (from Sweden) which requires half hour labour.