Why is my x0-y0 17" past home position?

It looks like you are G54, G10, and Current Position confused. With those settings, it would be hard to predict where it is going to end up. You are still in the CNC mode.

Make a note of your current settings, and then do this:

  1. Set $10=0 (from =3). This tells the controller to report workspace coordinates rather than machine coords.
  2. Home the machine.
  3. In the Console window, enter G10 L2 P1 X0 Y0 Z0.
  4. In the Move window, click on Get current position.
  5. Record the X & Y positions reported. Post those numbers here.
  6. Jog the machine to near the corner opposite of the Home position.
  7. Record the X & Y numbers and post those here too.

Once we see those numbers, we should know what we need to change in GRBL.

I also recommend you use Absolute Coordinates for positioning.