Sieg KX1 & Mach3 won't come out of emergency reset

[Jess]

Maybe the controller card still thinks there is a problem and won't actually allow any movement.

Could be; at least the geckodrive controller I have in my machine (not a KX1, sadly) won't power up unless the e-stop terminal is connected to ground (either via a wire or estop button).

Given that the estop being closed in normal operation isn't necessarily the obvious thing, when you say that you've tested the estop; does that mean that you've got continuity across the estop switch?