I was trying to install a new head unit and yesterday was successful in doing so. I drove the car for about 5-10 minutes and the music played great.

Today I was driving to work and the stereo still worked fine until I was in a parking lot and put it in reverse. As soon as I put it in reverse, the power went out to the radio, the AC fans, the lights in the cabin and the dash display lights. I checked all the fuses, none of them are blown. I removed the head unit and all the wiring and STILL no power to these components.

Any advice?