[MetroMPG]

Well, I put the spare DC-DC into the car on the weekend, and confirmed the smoke was let out of the previous one.

And I think I may have discovered another wiring issue that might (?) have contributed to the demise of the first DC-DC.

I have it wired on the input side in a 48v circuit that powers the contactor activated via the ignition key. I haven't confirmed, but it looks like that circuit may not have a "clean" off position. Seemed like there was some residual voltage on a wire that shouldn't have been live with the key off. Have to dig a little further.