Try to pinpoint the location of the dead animal by sniffing along the wall to identify where the smell is the strongest. A dead animal will most likely have fallen to the bottom of the wall, so smell along the baseboard.
Use a stud finder on the wall where you think the animal is to locate where the studs are behind the drywall or plaster, then mark the spots with tape.
Drill a hole in the wall in between where the two studs are. The hole should be approximately 1 foot above the bottom of the wall.
Insert the end of the camera in the wall and confirm there is a dead animal in there. If there is no animal, find the next stud, drill a hole as before and look for the dead animal until you find it.
Use a drywall saw to cut a 4-inch-square hole in the wall where the animal is located. Put on the rubber gloves and stick your hand in the wall to remove the animal and throw it away.