Just listening to the main system this morning while my wife was listening to the Muso QBII in the kitchen.
Suddenly all power to main system gone. No power anywhere except lights. Investigation revealed an RCD had tripped. Cause unknown.
The odd thing is that despite no power the QBII continued playing and showing lights! Anyway re-set RCD and power again but QBII now dead. Why? What’s going on?
Any thoughts? I checked the mains lead and it’s OK - fuse not blown Is there an internal fuse?
I thought my qb was dead, took it in the next day and just thought I’d try it and it was magically working.
There are no serviceable parts unless you hit it very hard with a hammer. The bottom Perspex bit is glued on and has to be separated using a lot of force. But Naim hq does service them.
If it just seems like a unresponsive cube of Perspex and metal then I think you’ll have to talk to your Naim dealer about getting it repaired.
Cause of RCD trip now established as a failed oven heating element. Ricotta and spinach ravioli lunch came out stone cold 
Does not explain why the Muso QBII is dead though.
Thanks @robert_h Just tried it again and it works! Panic over. No idea at all why it behaved as it did though.
… probably means it’s not on the circuit you thought it was.
Worth investigating further.