Thanks @ronotti1. That makes me feel better. At least now I know that there wasn't anything I could have done to save him.
You did a good job with him. Chickens just die sometimes for now apparent reason. I had one injured last Saturday and had to cull it. It somehow broke it's wing she was one of the trader joes chicks and they can fly higher than most breeds do--like leghorns. My guess is that she got caught in the netting somehow.
Not much you can do. At least this year I did not lose any to the heat!