Take it apart and find out. I’m guessing the tenderloins are for sure bad. Stuff closer to the skin/farther from the gut cavity will have cooled sooner, but their hide and hair are very efficient at retaining heat...
There is a difference between meat souring and actually rotting. If it’s just got a little bit of an off taste you may be able to salvage it by making a heavily seasoned sausage with a lot of fat mixed in or something like that. Also brining the meat can draw some of that sourness out.
If it were me I’d try those things in an effort to not squander all that meat but I’d also have a high degree of suspicion. Take apart a hindquarter and go smell the meat away from the animal, your nose will tell you a lot of what you need to know. Obviously if you think it will make you sick or if you try it and it does make you sick you should toss it.