Drove up to Flaggstaff today for a 2 day retreat. As I was leaving town, my "check engine" light came on. After an inspection of fluids, under the hood, ect. nothing was found and I continued on to my destination. All was well. The meet and greet in the hotel was good and, everything seemed in order. After the M&G, my travel partner and I decided to go into town to look around. As we approached my car, I hit the door locks and prepared to leave. I put the key into the ignition and .... nothing. The battery was completely dead and we weren't going anywhere.