This has been reported before. Most of the time there seems to be a problem with a wire harness/battery cable. There is a bad weld between the cable and the lug. I checked on some of the tech forums.... no message from Ford about it yet, but maybe in the future. Parts backordered (cable/wire harness), but some techs have figured out a way to fix for now. That seems like the most likely issue in your case too. There was probably a bad batch of cables.