Thanks guys! I found the short in the fan wiring (grr)
I have swapped in a mks base 1.5 board (Which I had on hand) to get to printer up and running...
... but it doesn't!
Problem 1: the x-axis just shakes, does not move. Sometimes it will move, but not smoothly.
Problem 2: all axes won't home! X will try to home, but Y won't nor Z. I can jog all axes.
Can any of you think of a fix?
(the 1.5 board has built-in stepper drivers)