Looking for large 3D printer

[curious aardvark]

yeah I had something similiar - try switching the x and y axis stepper motors plugs over.
I swear I got it right initilaly - but nothing homed until I swapped them over.
Sometimes the instructions tell lies ;-)

And don't forget to switch the endstop cables as well (I did - forgot, that is ;-)

If it's anything like mine it should home to the back left corner.

So one endswitch is on the extruder carriage and the other one is on the outside of the linear rail - took me a while to find that one :-)
Both shoukld have been pre-fitted.

what profile are you using for simplify3d ?

For the endstops you are homing to the Min '-' sockets.
they are on the right