I built my Prusa MKS3+ from the kit so I know generally how to assemble and disassemble my factory-built MK4. The one part that is unfamiliar is the extruder.
Prusa just published no-nonsense videos showing how to build the MK4 from the kit. Would have been nice to have these when I built my MKS3+. Anyway, I just watched the video on the MK4 extruder assembly so I now know better how it works.
Here is part one of the series on YT: https://youtu.be/OkRODkM2JNU?si=vpKlJfwdDjQeaogr