If when you try to home any axis and it goes the wrong way a bit and stops then we can only assume we either have that endstop unplugged, wired to nc or no when it should be the other way, or we have our endstop inverting set wrong. What is happening is the controller thinks the axis is at its endstop position so it tries to move it away from the endstop. If it starts moving and does not see a change of state on that min endstop then it will know there is a problem and just stop.