Nav map issue

Hi all:

I'm new to the forum, and have a problem with my '05 prius maps. I was poking around the secret service menu, and in my infinite wisdom changed the loading program for the nav system. I have the disc in the unit, but I have a screen that directs me to put in the correct map disc. I can't use the menu button to get to the volume screen. Does anybody know an alternate way to get to the service screen. I have been to the diagnostic menu, and see that the nav system isn't connected. I have tried resetting the codes as well as the memory from there. I also have tried disconnecting the DVD unit as well as the 12v battery, all with no luck. Lastly I went to the dealership and was excited to hear that this was a first. They wanted $125 to start diagnosing. Any help would be greatly appreciated, thanks in advance

Craig