I don't know of a reset, myself. Have you tried holding the power
button down for several seconds. I know the later stereos have certain
functions tied to that.

Alternatively, you could try resetting it by disconnecting the battery.
With the battery disconnected, turn on the headlights, and press the
brake pedal. This will ensure the electrical system is drained. You'll
lose your stereo presets and maybe get past this.

After that...I dunno.