Z-axis 0 level calibration
There is a screw to touch the z-stop at the picture shown.
First, screw the screw down to the end.
Then, do auto home.
You can see the screw is touching the z stop, it is now at the 0 level. But you can see the nozzle is above the platform with a big gap.
Then screw up the screw slowly.
And screw the top red button down at the same time slowly.
Screw those until the nozzle is slightly touching the building platform and the z-stop switch is just touching the screw slightly.It is better to use a paper sitting between the platform and nozzle to make it slightly touching.
If the level is not fit enough, please do the whole process again.