Ender 3 pro w/upgraded 4.2.7 BLTouch will not move on the z axis to home the z

Ender 3 Pro, upgraded the MB to the 4.2.7 one (silent) and installed a BLtouch. tried several firmware versions from Creality, but nothing seems to work. The X and Y home fine, but then it moves to the center of the build plate and the probe extends and retracts 2x without even moving on the z axis. I did follow the wiring diagram, so I didn't screw that up. I swapped the control wires of the BLtouch, which did nothing. About to throw the damn thing away and just manually level the bed again.Does anyone have any ideas?