How can I fix that?

Well first you have to confirm by visual and physical check. The you need to get a second person and multimeter that can measure continuity. You hold the meter to one lead of the sensor harness they hold it to the same lead on the main board and you wiggle the harness to see if the continuity breaks. You repeat the process with the other three wires in the harness.. Unless you get lucky and just find it was loose.

So every time I print on this XYZ DaVinci 1.0A, it prints fine in the middle of the y-axis all the way across the X-axis. But if it goes out of the middle of the y-axis, it starts moving each rotation more and more to the front left. I've tried this with a lot of 3W files, and I've printed those same files on other printers. Support hasn't helped, so I was hoping someone else would have some kind of clue. There's a picture of what I'm talking about attached.

For your problem, you probably have a damaged harness or loose connection on your Y endstop..