There’s not much to it, just make sure to have the latest firmware on the USB drive (found here: Snapmaker 2.0 Firmware Updates and Downloads v1.14.2), swap in the ones marked 8mm on Z (the two vertical ones), and the 20mm leads for X/Y (2 for Y under the bed, 1 for X that the toolhead attaches to)
The lead is marked on the side:
After swapping in the new rails (3x20mm lead for Y/X, 2x8mm lead for Z) boot up the snapmaker, and ‘run’ the firmware .bin file to update the firmware on the rails. You should be good to go after that, if not, you can try downgrading the firmware to 1.13.2, then back up to 1.14.2.