[MPaulHolmes]

I'm pretty sure I can now eliminate the problem of having to turn on controller low power section before pre-charge resistor. Just 1 15kOhm resistor for each mosfet, from gate to source. That will keep gate at 0v when the controller is off, rather than having it floating. I think that gate was floating, and allowed power to go from the capacitors from drain to source. The current must have been huge for an instant, killing them!

Mosfets are a funny thing. Sure, put 200 amps through them, sure, do that at 150 volts! No problem! But don't have gate to source voltage go over 20v for an instant, and don't allow a large current surge for even a few millionths of a second! They are so touchy! Geeze!

I have 1 mosfet left. I shall be super careful with it. My wife is buying me a couple more practice mosfets. They're 3 bucks each so it's all good.