If the starter's gear doesn't mesh correctly with the ring gear on the flywheel it can be difficult for the starter's gear to retract. I suspect that is what happened the last time on your first starter. It then got spun like hell by the motor. Why it went dead then later tested okay I cannot explain.
The flexplate(flywheel) on auto trans cars can ring like a bell when starter enagagement/disengagement is rough.
A few things I'd be checking are that the ring gear isn't tore up by removing the starter then turning the engine by hand to inspect, make sure the starter is/was squarely seated and tight and checking tightness of the torque converter, transmission and flywheel bolts. Anything that could cause a misalignment between those gear teeth.