Your printer suspects that everything is not in perfect order with your end-stops.
Wiring issue
Make sure there is not a wiring-issue with the X/Y end-stop on the mini RAMBo board.
Go to the LCD menu -> Calibration -> Show End stops. Once you are in this menu, manually click on the X/Y End-stops one by one. During this procedure, monitor if there is an appropriate change on the LCD.
Once pressing X end-stop = X shall change from 0 -> 1
Once pressing Y end-stop = Y shall change from 0 -> 1
If the procedure above went alright. Then one of your end-stops just can not be reached/triggered. That means there is some assembly/mechanical issue that prevents proper movement.
X/Y End-stops out of position.
More common is that the X/Y End-stops were not installed correctly during the assembly.
The easiest way to check that is by doing the following:
You can easily click the end-stops when manually moving with Extruder or Heated bed, by hand.
Inspect that nothing is blocking the path around the Smooth rods and Heated bed cables.
With MK2S, it is wise to check that your Extruder cables are not hitting the mini RAMBo box. If they are, then re-adjust them.
