Have you tried dropping it from 2.5' on the butt end?
Sorry to hear of your plight and I hope my attempt at humor did not offend you.
My shooting buddy has a 500 Smith and had the exact same symptoms, but from an entirely different cause (probably). Firing a Buffalo Bore round, the primer got pierced, blew hot gasses back through the firing pin channel and managed to break a small part in the action (among other damage).
The gun would not cycle or open the cylinder. Very little movement of the cylinder release either. We took the side plate off and saw the broken pieces and put is back together. We took it to a local S&W authorized gunsmith/repair center who sent it back to S&W. My friend had it back in a couple of weeks. No charge, but your case may be different.
My speculation is the shock of the impact might have broken something in the action.
Good luck,
Lost Sheep