Have no fear! It's not dead, just do a soft reset! Use a pin and hold the soft reset button for 5-10 seconds (the reset is not on the face, but in the hole at back where the unit connects to the base; opposite side of the gold circle, up just a little from the green strip). Apparently the battery shuts down if it's overcharged, so if you charge it for more than a few hours it might not turn back on again.

Reset it and you'll be on the road again!