Common causes of no sound with these are:
Link plug “hot plugged” which can cause one of the power rails to be shorted to the ring of the DIN socket.
Failed HDCD encoder IC, which often takes both DACs with it.
Whilst we can in theory fix all of the above, the gamble would be the transport mechanism surviving the round trip.
If that is a risk you are willing to take, you would need to convince your dealer & plead with Naim tech support to issue an RMA.
Good luck with whatever you decide!
Regards
Neil.