i think just in case, he should reflash his phone several more times, just to make it sure that usb works :P
kidding, yes, i agree that it might be hardware fault, but seems like nokia didn't do drivers very well.
some n9's/950's had similar problems with headphones (mine does)
however service should do the trick (unless he's happy like italian guy who bought n9 in swiss and had tons of problems)