Nissan Repair Questions? Ask a Mechanic for Answers ASAP
The first port of call would be to check for software updates for the unit which you are obviously trying to do via your Home Wireless Connection. This can take time often up to an hour!. I have found that tethering the unit to your mobile phone if you have enough data is sometimes quicker due to less things getting in the way of the signal.
If there is still a problem with the reception of DAB the you can carry out the self diagnostic through the unit and check that all of the areas are showing in green. If this is ok then it may be a faulty unit or aerial mast and as such will require new as applicable.
The Software Updates can vary depending on what is actually updated on the system.
Please see attached for self diagnosis.