Going back several posts, if you shorted out one pole of the motor, then it should survive as the driver is current limited. If you shorted adjacent poles the outcome could be problematic and to work it out would take a little time via vector anylises. I suppect that this is the case and you have exceeded the voltage ratings of the driver. Since the driver is probably dead, disconnect the motor, turn it on and measure the motor voltages which should be slightly lower than the supply voltage. Disconnecting a stepper while energized causes very high back EMF which could be hundreds of volts and will kill the driver output chips every time.
As for changing the ratio, I have modified the Sketch so that I can have three different ratios eg 90 to 1, 60 to 1 and 40 to 1 via menu selection. With my modified Sketch, you can have any ratio with in reason just by changing one number. I have made 5 of these controllers for different people who couldn't work it out for themselves.
Happy to share both Sketches with any one who wants them. p
Bruce
WESTERN AUSTRALIA