Can you turn the engine over by hand ?
have you tried with the spark plugs removed ?
If you crank it with the spark plugs removed, make sure they are well out of the way because a stray spark and fuel being pumped out of the plug hole = flame thrower .
If you still can not turn the engine over by hand, try removing the belts from the engine pulleys
Let us know what happens for more instructions as I have no intention of reproducing the 250 page JD technical manual here
