Trying to build autosteer with PCBv2 - Motor would not turn

[Radmuffins]

Pin D6 to ground,

Head scratcher

That tells you that nano works and sketch is good. Yes try shorting steer switch on PCB if that works then your switch is bad. If not see if your optoiso is solder good, small nouch is facing up and is resistor good value. [steerswitch]

And you can solder switch before resistor and other wire to ground and you will bypass opto.