Radio would not come on

I have a model IV with solar but that should be irrelevant to this: I started up this morning and all was normal, no weird beeps or lights, going to work. Pressed the radio volume know but the radio would not come on. The nav ususally says "Audio On/Off" but nothing appeared there. I tried the steering wheel Mode button to turn it on. Nothing. The Open/Close switch on nav/cd worked. Did not play with it when I got to work. I was thinking maybe I blew a fuse. But when I got in to come home, it worked perfectly. So just a one time quirk so far (I have had the car for 3 weeks with no other problems).