Makerbot endstop pin number Function Duet 3 IO_x pin marking Duet 2 endstop pin marking 1 VCC 3V3 3V3 2 or 3 GND GND GND 4 Output IO_x_IN STP Unfortunately the pin markings on the Makerbot endstop board are hidden underneath the connector. Pin 1 is next to the long edge of the board that does not have the microswitch on it, and pin 4 is nearest the edge with the microswitch.

https://docs.duet3d.com/en/User_manual/Connecting_hardware/Sensors_endstops#makerbot-mechanical-endstop-v12

Can you see markings on the endstop indicating which pin is which?

If the description from the documentation matches your endstop pin 1 would be on the right side of the endstop in your picture with the red cable in it. Which based on the table should be VCC 3.3v, but you have that wired into the middle pin on the Duet connector, which is ground.

The blue wire in the middle should be ground, but you have it wired to 5v external.

Pin 4 with the green wire is signal and it looks like that one is correct.

So I think you're basically shorting the 5v rail.

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So I think you should move the red wire to the 3.3v pin on the duet connector and move the blue wire to ground. But to be sure you should identify which pin is which on the endstop itself. You may need to lift up the white connector a little bit to see the silk screen printing under neath it. Or maybe they have it labeled on the back side.