As long as M420 Z command not supported by firmware I want to turn off bed levelling completely, but when I use M420 S0 hot end crushed into printing bed, how to run it properly?
Like here: Maximum Y Position 347mm? you could move the nozzle to the correct Z height and use G92 Z0 to make it the Zero position. There is also M206 - never played with it, but it may also do the trick.