It may have stripped the teeth of the input,if so there will probably be more internal damage.

If the input shaft was broke, it would not spinning the internals. so with the grinding it sounds to me like something in the clutch area is broke. not being there its really hard to tell what is wrong. keep us up dated once its removed. If you don't buy let me know. I've been wanting to convert mine to a manual. ;)

If it stripped the teeth off the input(teeth inside the transmission it would grind and not move) I have seen it happen on car transmission's.Just a thought.