Welcome to the site and glad you could join us.
It would seem that when the fans stopped, you overheated and, as a result, you've compromised your head gasket. White smoke is nearly always indicative of coolant leaking into the combustion chamber and the way it typically does that is through/around a failed/failing head gasket.
I'd recommend a compression and leak-down test on each cylinder to figure out where/what is compromised.
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