This is a 2003 G35.

The NAV display has stopped working. It has gone black like there is no power. I have checked the fuses by the driver's left foot and they appear to be OK.

Is there another fuse box?

Any other suggestions on why the display would suddenly go blank?

thanks

 

behind the battery

 

The Nav system has 2 fuses associated with it (see picture 1).

The first one is the main fuse - if that was toast, you'd have bigger problems. The second one is in the fuse box inside the car (see picture 2).

If they are both OK, you may have a harness problem (disconnected). Have you ever had the HU out? If so, you may not have clicked the connectors back in completely. If not - OhOh - back to the dealer.
Edit: It looks like fuse #12 is involved also -best to check them all.