Q: Engine ceased! on 2005 Ford E-350

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Just bought a 2005 Ford E-350 extended wagon, with 60k km. Been driving it for no more than 3 months. It's been parked for about 2 weeks. Went to start it the other day. It ran for a few minutes, I put it in reverse to back it up and it suddenly stalled. Wouldn't start. Tried boosting it, nothing. Called the garage. He checked the battery, the starter, etc.. The engine would not start. Is completely ceased. Can't even crank it manually. Believes it to be an internal malfunction/failure. How can this be? On a practically brand new van?
(2) Answers
Try pulling your spark plugs then turn the engine over, just in case water or fuel entered one or more cylinders and filled it enough to cause a hydraulic lock situation.