How to level laser bed?

Upgraded to the 10W laser and all was working good until I pressed go to work origin and the head crashed. That should not happen, but I was glad I bought the emergency stop button.

Repeated all of the calibrations in the setup screen.

The laser cutting the top half of the print area fine and then fading towards the bottom half. Pictures attached make it clear the bed is not level.
There seems to be no way to fix it other than tediously trial and error shimming. Is there a way to level the bed as is done with the 3D print module? Can only set the bed height at one point in the middle.

Checked other posts on the forum and saw no real resolution for the laser, only for the CNC.

Level the CNC bed and then use it to laser on? Use a sacrificial board for cutting?

Or do what I did and shim the laser bed under each mount