How to solve Ender 5+ weird Z-axis behavior issue? Before you select if you want automatic or manual leveling, the printer runs a routine to determine the Home Z-axis at the center of the bed.
This starts OK, then the level goes to maximum (of the screw) and stops. Click on the + or - button for the Z-axis does nothing. I tried to flash the firmware again (I flashed it previously to fix the auto-leveling stalled as recommended by Creality) with no effect.

As you can see in the image above, the bed has lifted up the print head. That is repeating in printing, leaving scratch marks on the bed.
Ok. So I solve the issue by myself. So to explain the problem a bit further: I had to install a new firmware. That completely reinitialize the z-axis, making the bed goes to the maximum of the screw to the point it lift the print head when I clicked on the Leveling button. To reverse the initialization of the z-axis, I click on the Leveling button,  manually lower the bed by clicking on the upper arrow, then, click on manual or auto leveling, then click again on leveling and start over. At each iteration, the starting point of the bed gets lower and lower to a normal position. I had to do 4 or 5 iterations until I get the desired result. Bonus point: when you click on the move button, the bed goes down if you click down of the z-axis. The opposite behavior is happening in the leveling menu: so you need to click a couple of time (between 10 and 20 time for me at the first iteration) before the bed isn't in contact of the print head.