Update
Well here's an update. My unit had a little episode.
I unplugged the radio and moved it to a new spot. When I went to plug it back in, the display malfunctioned. It showed garbled/mixed characters and junk on the screen and none of the buttons worked. After hitting a few buttons randomly the backlight came on but the display was just blank. :roll:
The manual says nothing about how to reset the thing.
After fooling around with it for a few minutes, I found a solution. By pulling the batteries out of the radio, unplugging the AC plug (but leaving it still hooked up to the radio), and then plugging it back in, I was able to bring the unit back to life.
Now it's working fine again, and my FIPS codes were not lost. So, in case this happens to anyone, now you know how to fix it.