I'd try the baking soda or charcoal after the cleaning. What ever bacteria were there should be dead after sunlight,bleach, and now oxyclean, but their "by products" could be bonded to the plastic. The baking soda or charcoal will absorbe the funk and help.
Last year the freezer of my keggerator had a similar event occur and it reaked of death. Unknown to me my parents decided to store beef in the freezer, but it isn't self defrosting. Needless to say when I unplugged it for the winter and opened the door to the freezer, I was lucky to have my trash bucket next to me. Ended up cleaning it with bleach and putting a charcoal damp rid in it and about 4months later opened the door and no smell at all.