The z-axis motor is not bound and is moving in both directions, just not after homing. I am also assuming the z-axis is supposed to be able to move down after homing, as the instruction for setting up the CRTouch specifically says to home the head, then to find the z-offset by lowering the z-axis. In the case of only the Z-axis of your Ender 3 failing to home, we can immediately tell that the Z-axis endstop is the culprit, meaning that either there are problems with its wiring (especially likely if you have been working on your Ender 3 lately) or the endstop switch is not functional anymore. A faulty microswitch stopped my brand new ender 3d printer from working properly. I could have got a new switch, but the fix was quick and easy. The z axis The reasons that Ender 3 Z-Axis is not moving could be printing scale issues, motherboard failure, or eccentric nuts problem. To fix the eccentric nut issue, loosen them and do tightening them. For avoiding the printing scale issue, loosen the screws on the lead screw bracket. It does not move at all on the Z-axis and remains 3 - 4" above the bed during and after Auto Homing. Here's the detail : I installed a Creality Ender 3 Pro New Upgrade Motherboard Silent Mainboard V4.2.7 with TMC2225 Driver Marlin 2.0.1 & bootloader pre-installed & then a Creality BLTouch 3D Printer Upgraded Auto Bed Leveling Sensor Kit (the 3 - Adjust the Z-axis limiter switch. On your Ender 3, Ender 3 V2, and Ender 3 Pro, you'll see two M5 bolts with two M5 t-nuts. Carefully loosen each bolt just enough to slide the Z-axis limiter up or down the 2040 aluminum frame. You'll likely only need to move the Z-axis limiter switch up 1 or 2 mm to correct your issue. ZbUOB.

ender 3 z axis not homing