An automatic transmission will never “reverse drive” an engine. When you shut your engine off in an automatic transmission, thats it, the engine stops spining which in effect takes away all hydraulic pressure to the transmission releasing friction elements which are engaged. This is because the trans pump is no longer turning. The internals of the transmission are still spinning due to the driveshaft/s still spinning. These parts are being damaged because there is no atf lubricating them.