Mamba Max ESC Failure

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I'm running a Mamba Max ESC / 5700kv motor in a converted HPI MT2 with a 3S lithium-polymer and conservative gearing. It's been working great for about a year now. I was running it around on some dirt when it suddenly lost power - no servo or motor response at all. The motor was warm, but not scalding hot. So the usual suspects were ruled out:
Battery: tested fine, also tried another battery.
Receiver: tried another receiver, no change.
Motor: All three windings show back-emf when spun, and it doesn't feel abnormal.
ESC: Wiring looks and tests fine, main caps don't show as short circuit. No smoking/melting/exploding visible.

The ESC will connect normally via Castle Link, and flashing works but is unhelpful. There are no LED's and I also get none of the sparking which I normally get when I plug in a battery, which I assume is current inrush for charging the capacitors. There is no voltage on the wires to the receiver, either.

It seems like an internal BEC failure to me, but of course it is possible the FETs died. Or it could be something completely different... Anything I can do here?