Hi, thanks for the reply. The problem, though, is that the navigation and radio won't even turn on at all; this includes the CD changer. It is completely dead no matter which buttons or knobs I press. I checked the fuses and they all test good, both under the hood and on the fuse panel to the left of the dashboard. I'm guessing that 12V is not getting to the unit at all or else it got fried or confused or the car computer has shut it down somehow when I replaced the battery. I have not yet pulled the unit out to see if there is 12V on the supply wire.
I wouldn't have expected the unit to be completely dead if it was just locked out. Could there be another fuse or fusible link somewhere to check? All other systems in the car seem to work, even those associated with what I think is the same fuse, like the rearview mirror control.
It's been suggested I have the computer reflashed, although I don't really know what that means or what the effects of doing it are.
Thanks. I'll give it another look and check for 12 volts.
I just got the radio removal tools today and was able to pop the unit out of the dashboard so I could check 12v at the input to it. I discovered there is in fact a 15 amp miniature automotive fuse in the back of the RNS-E. I replaced it and everything came back to life. I guess we both learned something here. Thanks for your help.