Need some help. The computer in my Expedition died and had it replaced . Truck ran fine coming home from dealer. Went to start it a couple days later, and turns over but will not fire, theft light flashing. Tried again later fired right up with either key. Then nothing again. I did notice it runs through warning light sequence and then the theft light goes out and it starts, or heft light starts flashing and then no start. I would think it is probably Pats related, but don't know where to start. I guess it could be ECM related?