Unfortunately my first fear is that with the pop sound and the stall...it sounds like the timing belt
Easiest way to check is to pull a fell bolts out where you can GENTLY bend the cover enough where you can peak in with a flashlight...no belt...then thats it.
If the belt is there...it doesnt eliminate it....it could be stuck on the top gears...however I would refrain from trying to crank it until you 100% eliminate that...because you dont want to put a valve in a piston or something
