I mean it's a headache just trying to figure it out through typed words on the internet, it's hard to grasp what is going on here.
As far as the spark plug goes, I highly doubt that it detonated to the point it just 'disappeared'. There's no sign of the spark plug right? I find that very improbable. Shine a flashlight into the spark plug hole and see if you can see anything that doesn't look right, like metal chunks. The top of the piston should look black from carbon, which is normal.
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