With no endstops pressed, send M119 to the printer, does it say the endstops are L or H
If they are showing H when not pressed then you need to change the endstop switch types from normally open to normally closed or vise versa, in the firmware config tool under mechanics/endstops.
What size pullies are fitted on X and Y motors, how many teeth ?
If they have 16 teeth then 100 is correct for X,Y steps.