Apparently,it is possible to manually over-ride the electronic doorlock system from inside the car,but he didn't know about it,which makes you wonder if corvette is to blame? (Unless this was suicide?)
http://www.independent.co.uk/news/world/americas/corvette-texas-man-and-his-dog-die-from-heat-exhaustion-after-getting-trapped-in-luxury-car-10313149.html