I was up all night, and decided at 5 am to fix my Printers input, because it had broken a few days ago. So I replaced the connector, but confused the polarity, yes I know, clever me, and I broke the board.
It wouldn't work from the power input, but it still would work from a USB, the motors wouldn't work of course.
My board was MKS Base V1.2
Sorry for the quality of the pictures, my phone has 5mp only with no manual focus and terrible autofocus.
Step 1: Step 1. Check the Fuse
Check with the continuity function of your multimeter across the F3 Fuse (near the power input)
If you have continuity continue to the next step.
otherwise replace the fuse.
Step 2: Step 2: Replace the Regulator
Disolder the regulator, clean the pads, and make sure you don't have any short circuit.
Solder a new regulator (L5970D) make sure you don't have any short circuits between the pins of the regulator.
PS: Be careful the resistors and capacitors next to the regulator so that you don't disolder them. I had to fiddle with R5, because I wasn't careful.