You say you tried to turn the engine over by using a breaker bar and it wouldn't turn over? If that's true it sounds like a hydraulic issue. Lately a friend drove his Cobra home from the track and it was running a little rough. Next day it would not turn over with starter or breaker bar. Removed the plugs and turned over the engine and watched "old faithful" come out of a couple of cylinders. Blown intake gasket.