I don’t have any experience with your particular printer so my suggestions will be more generic. You will have to figure out what applies to that printer.
First, some explanation of what it’s doing and why. When the printer tries to go to it’s home position, it usually move the X axis first, then the Y, then Z.
Z is the most risky since moving the wrong way will drive the print head into the build plate or glass, as the case may be, so the safest approach is to first back the Z-axis away from the build plate and then slowly lower it until the limit switch is triggered. You are seeing the backing-up part but not the movement down until the limit switch is triggered. That means only one thing:
Your Z axis limit switch is already being triggered.
Check that there is nothing hitting the switch and that the switch lever can move freely.
If it can move freely, check it with a multi-meter. It should change resistance when you press on the limit switch.
If it doesn’t change resistance, then the switch is bad.
There are two possible ways the switch could be implemented: Normally Open (notated as ‘NO’)(high resistance when not being pressed) or Normally Closed (notated as ‘NC’)(low resistance when not being pressed). There is a slim possibility that they used, or wired it as, a NO switch when a NC switch is what the printer is expecting, or vice-versa.
It’s also possible, depending on the design of the switch module, that the module that has the switch mounted on it may have there pins representing NO C NC (C represents “Common”). So, if that’s the case, one of the two wires should be on C and the other should be on on NO or NC. Whichever one it’s on, change it to the other.
It’s possible the other end of the wire has come out of the connector on the controller board. You may have to open the case and verify that it’s plugged in properly.
There is a slim, very slim, outside chance that the firmware on it is not correct and has been configured to expect the wrong type of switch, but I would lean 99.9% toward either a wiring error or a defective switch. Do not try a new firmware until you’ve verified the switch works and the wires are hooked up correctly all the way from the switch to the motherboard.