Hopped in my car one day, attempted to start it, no "engine turn over" at all, reminded me of when the battery is dead.
However, after "releasing the key" noticed an odd noise coming from the engine, like a spinning motor that won't start (kind of like a stuck on windshield wiper fluid motor).
Looking under the hood, appears the noise is coming from "the starter region" and the starter itself was getting very hot.
Disconnected the battery and the noise stopped. Noise continues even without the key in the ignition when battery is connected.
97 Honda Accord in this case.