One things to check when that happens (I have been struggling with it repeatedly over the past month) is if the bearings on the smooth rods are even with the top of their bracket, or if they have gotten pulled up and the bearing sides are visible. (It should be flush on both the right and left sides.)
If you had a waste collection failure and the waste was deposited somewhere randomly inside the printer, something in the latest firmware version appears to no longer stop when it encounters resistance and it will keep trying to crank the build plate down to it’s lower limit. The result presents as a build plate leveling failure of Z axis homing error. If you look closely when attempting to calibrate Z, you can just see that the tip of the nozzle may not be actually contacting your build plate, at least in some positions.
I recommend checking to see if the top bearings on the build plate assembly (smooth rods) are still still flush with the bracket they are press fit into. There is a process in the Wiki on how to resolve. When you follow it, check the other side and press it down too, to get as close to identical as possible on the left and right sides.