Originally Posted by SouthArk370Z

Ah. Since the Nav beeps, it's getting some power ... but there may be more than one power feed.

If you don't find a blown fuse, then you may want to pull a battery cable and hold the brake pedal down for a few seconds to kill power to the whole car. This may reset the Nav. This will reset the tuning params in the ECM, so you will have to drive around for a while before the car will run normally.

If that doesn't work, download the FSM and start reading.

Edit: Check the wiring between the Nav and the radio.