Machine frozen after broken sensor cable?

I just finished assembling my new CNCRP4896 last night and was so eager to turn it on that I skipped setting up my router and left my cable tracks open so it would be easier to wire the router later. I hooked up my computer to the Avid electronics box, set up Mach4, and made it move a bit, got excited, went to bed.

This morning I fooled around with it some more but since the cable tracks were open, my cables were flopping around. One of my sensor cables (X) got caught on the tray and the machine happily ripped it in half without skipping a beat. Whoops!

Anyway, so at that point I didn't know which sensor I had killed so I figured I'd jog the machine manually around from Mach4 and keep an eye on the sensor readouts to see which one wouldn't fire. Turns out I jogged it too fast because I simultaneously learned that my X sensor was the unlucky one and caused a big thud and now refuses to move at all in any direction. I've tried turning it off and on again, pressing the emergency stop button, and resetting Mach4 to no avail. Mach4 doesn't show anything unusual, but any attempts to jog it manually don't work at all.

I assume I've tripped some sort of current failsafe (presumably it had to push harder against the rubber X stopper) inside the electronics (all the usual LEDs are on and the fan still spins, so I don't think I damaged anything too badly) and there's a reset procedure, but I can't figure out how to do it. Anyone know? I've ordered a replacement sensor cable and for now I can splice the broken sensor cable manually until that arrives, but I need to apologize profusely to my electronics box first and it's not having it.

This ultimately isn't much different from crashing the machine into a firmly mounted workpiece, so I assume the process is the same, but I don't know what that is.