Your radio may have a lited panel. The other wire may be to the lamp inside and hooks to the headlamp switch or panel lamp resistor.
If the buttons don't move the needle and the knob does the they may all be set to the same channel. Move the needle with the knob and pull out on the button you want to set for that new channel, then push it back in to set it. Will the buttons now move the needle?
Or yea what truckernix said. I guess I should read all the posts first. Then type my 2 cents.

I didn't do it, no one saw me do it, you can't prove anything! "Bart Simpson"