Stepper motor not rotating, just sounds like it is going back and fourth

Always check the motor windings are as you think with a multimeter before connecting, always connect up before powering on. Always check the current setting is sensible before connecting a motor. You can power up a stepper driver with nothing connected to test the current setting as documented by the vendor. Otherwise only power up with correct motor connections.

Connecting wrongly, or connecting/disconnecting while the power is on can totally destroy a stepper driver. Powering up a motor with too high a current setting can rapidly cook the windings.

At full current setting a stepper will get pretty hot, BTW, this is normal.

Running at down to 50% current is doable, go too low and you may get problems.

Lagom: Very helpful that you point that out, because Pololu shows the wiring wrong on some stepper motor diagrams(!) and so mine were just twitching around until I read your comment.

Interesting. Would you be kind enough to post a link to the page with the incorrect diagram?

...R

Yeah, sure, this is the motor

Black A, Green C, Red B, Blue D

Generic text with any motor: "The above diagram shows a standard bipolar stepper motor. To control this with the A4988, connect stepper leads A and C to board outputs 1A and 1B, respectively, and stepper leads B and D to board outputs 2A and 2B, respectively." (so I assumed this is a generic connection advice for the other driver boards)

and this is the driver

A1 A2 coil one, B1 B2 coil two

Specific text: "The two sides of one coil should be connected across OUTA1 and OUTA2, and the two sides of the other coil should be connected across OUTB1 and OUTB2." (what you said above).

Lagom: Yeah, sure, this is the motor

Neither of your quotes "The above diagram shows..." or "The two sides of one coil ..." appear on the web page you linked to so I don't really understand what is causing confusion.

...R