There may be a chance that the flywheel bolts sheered off. If you try to turn the motor over by hand and the trans is in gear, it may turn a little and then bind up on the broken bolts.

 

it would not have been from turning the key off or popping the clutch. something else happened then. don't matter how "quick" you pop the clutch-- unless you were going down the road at highway speed and put the trans in a low gear-- and at that it would have most likely fired up for a bit before you got a he11uva loud noise..... if my stick vehicle dies while cruising, I don't touch the key, I just pop the clutch, in a gear appropriate for whatever speed I am coasting.....

 

Here's another thing to check. It may not be your engine that has the problems. You could have broken a. The flywheel bolts, b. Your clutch pressure plate, c. Your input shaft.
also pull your timing cover and see if you broke your timing chain. Being able to spin the engine 90 degrees in total may mean the Pistons are bottoming out on valves that are stuck open because the camshaft isn't turning with the motor. I really hope that isn't the case because (pop) starting the motor would've bent the valves that were stuck open. Good way to check for bent valves, remove valve covers, unbolt and remove your rocker arms, then look to see what valve tips are sitting lower than the others.