WOW. That is really tenacious behavior, but racoons are like that: once they find a promising food source, they will go at it until it is either gone, or they get trapped. The thing with the can winding up on top of the lid was probably due to the fact that it was in a corner, and if you can imagine 3 good-sized racoons moving on and around it, it is possible that the can got pushed onto the lid in this way. I say hang the can from the ceiling, not near any walls or corners or windows, About 5 feet off the floor, with a simple hook for you to get the can down at feeding time. Or just bring the can into the house.