@psots have you checked the location of the external vs internal 5v jumper? If the board was previously setup to use an external 5v supply, I believe you would see what you're seeing. In this case, you just need to move the jumper. Or the jumper could just be missing.

Is it possible you just switched to the latest version of PrusaSlicer? Starting in version 2.4.1 (I think -- I might have been 2.4), by default they send the commands to set the feed rates, accelerations, and jerk. This had me completely confused for a while, as I had just fixed a hardware issue on my printer, so naturally I figured I must have messed something up.

If you have switched recently, go to the printer settings tab, and select Machine Limits in the list on the left. Set "How to apply limits" to "Use for time estimate". That will revert you to the former behavior.

@dc42 the 3.3V rail measures 3.31, so that's OK. The ADC is probably damaged.

Thank you for the response. I had reached the conclusion that I had damaged something, and I don't have the tools or skill to repair the board. So I guess it's live and learn to be more careful, and be thankful that the board isn't more expensive.

I should have added that I run external 5V to the Duet board to allow my to control PS_ON

While in the process of installing a new extruder I seem to have cause a problem. The most obvious symptoms are the VIN is reading 36.3 volts. Checking it with a meter reads 24 volts as expected. Hot end temp is reading 2000C and bed temp fluctuates ± 10C centering around 92. No difference in reading with or without the thermistors attached. MCU temp is reading 422.6C and it feels cool to the touch.

Printer is a RailCore II ZLT. Duet2 Wifi is running Firmware 3.3. I disconnected the Duex board and it didn't make any difference.

I verified the fuses were at least measuring 0Ω with a meter. Any idea of what is wrong would be a help. If the board is fried, at least I'd know I need a new one.

My config.g file:
config.g