1) Power on
After checking all wires AGAIN, and with the bed set aside where you can see the Duet board, attach the power cord and press the power on switch. KEEP your finger on the switch and if you see, hear, or smell ANYTHING you don’t like, turn it off immediately.
2) Verify Lights
You should see the red and blue power/status lights on the edge of the board (top edge in the picture below) come on and change for a few seconds as the board boots.
You should see at least three of the four endstop lights come on (the fourth depends on your z-probe, more about that below). These are red lights between the motor connectors (lower right edge in the photo below)
3) Test Switches
Use your fingers to press each endstop switch at the top of the tower. One of the lights on the board, near the motor connectors, should go off and on as you click the switch. It should stay on when you release the switch.
Use your finger to press the Z-Probe switch. The fourth light should change. It may be on or off when you’ve released the switch (more about that later).
Seriously. Power off, take a pause, say “WooooHooo” loudly enough that your family looks at you funny, have a beer, whatever works for you.