Intermittent fuze blowing

[Arfa]

2015 V60 D4 Business edition, it has the larger central display(I seem to recall?) and reversing camera plus Winter pack.
Hello there. The problem is intermittent failure of a 40 amp (!) J type low profile fuse in the smaller fuze box on the RHS in the passenger footwell. Sorry I can't remember the fuse number. When it fails it takes out the central display, and the radio plus the rear parking sensors. It may well take out the reversing camera as well, but given that the display is down, who knows? Nothing else is affected. For what it's worth diagnostic tests by two garages, one an independent Volvo specialist don't find anything useful. The wiring itself has been checked from the engine compartment through the fuse boxes and into the central consol. The fuse either fails on shut down, or on switch on. It can last for many hundreds of miles, several weeks, or it can fail hours after changing, like it has today. I found a volve pdf file with the wiring diagram for the car somewhere linked from this site but it pretty much leaves me puzzled as to what this could be. The wiring itself looks in very good nick and no water leaks or anything like that.
My best guess is that one of the units connected, like the infotainment, has some kind of internal problem. Before I start to delve inside the console anybody seen this one before?
Cheers, Arthur.