My Carvey died in the middle of a job and looked completely dead. No blue lights, no response from the front button, nothing. I have the earliest version of the carvey with the internal power supply.
I checked the power first and found the motherboard was still getting 48V, so the power supply was not the issue.
At first I thought the controller board was toast, but I took a multimeter to it and discovered that the 24V rail was reading closer to 4V. I unplugged all the molex connectors on the motherboard and it jumped back up to the real voltage, so I went through them systematically and plugged them back in and was able to identify that J7 was the problem.
This post was helpful and on little more than a hunch I figured it might be the 24V spindle LED connection that was shorting out. I clipped pins 9 and 10 on the gantry connector (obviously with the power off)
After that, the Carvey came back to life. I’m not sure which wire was actually the problem and his isn’t exactly a proper fix. But I can live without the spindle LED and this is a lot better than hauling it down to be recycled!