I'd suggest dropping the oil pan and do a close inspection of the area around the rear main bearing cap. Hopefully, something is just jammed, without any permanent damage to the block or the main cap. Loosening or removing the main caps might free up the crankshaft to get at least part of a turn. If the crankshaft needs to be removed, a lot of the front end has to be dismantled, possibly removing the harmonic balancer, timing cover, and the crankshaft timing gear, if not doing a complete disassembly.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!