Koerk, you should probably take this to it's own thread.
When you tried to turn the engine by hand or with the crank handle did you move in BOTH directions? It is very important to move the crank both directions when freeing stuck rings. Did you try prying carefully on the flywheel teeth in BOTH directions. If not give this a try.
What was the cloud of white smoke when dying? An overheat?
The biggest deal in getting a stuck engine to spin again is patience and constantly moving in BOTH directions.
Any info may help.
Dave Neptune