Actually I figured it out, I had autoprobe in the firmware on, but had no endstop in the autoprobe pins, so when I checked M119, it showed Z_min as always high and thus Z would never decrease in value. It is fixed now though Thanks.

However, I am having issue wiring up my Geared Stepper Motor from Kysan. I purchased it from Tridprinting. The schematic is located here: http://www.tridprinting.com/Electron...perMotor-1.pdf

The plug I received are reversed though. I am unsure on how to wire it to my RAMPS board.