If you selected MKS gen 1.3 board in the config.h then it uses the same input pins as the ramps.h.
I would guess you have a short circuit on the 2 analogue pins 13,14 of the processor,look for blobs of solder ,failing that, ask for a replacment board
I would guess you have a short circuit on the 2 analogue pins 13,14 of the processor,look for blobs of solder ,failing that, ask for a replacment board