Bad origin

If after a firmware upgrade (Marlin, TH3D, …) your new origin position is the opposite of the endstop and you want to fix this issue, you will need to edit the configuration file and reflash the printer.

Marlin 1.1.X and 2.0.X

In the file Configuration.h, lines 506 to 508, change the endstop position to use XMIN and YMIN:

#define USE_XMIN_PLUG
#define USE_YMIN_PLUG
#define USE_ZMIN_PLUG

You will need to disable steppers invert from lines 847 to 849:

#define INVERT_X_DIR false
#define INVERT_Y_DIR false
#define INVERT_Z_DIR true

And finally you need to edit the correct home direction from lines 873 to 871:

#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

TH3D

In the file Configuration_backend.h change the lines 2983 to 2985 to use XMIN and YMIN:

In the same file, lines 2000 and 2001, change steppers invertion to false:

You will also need to setup the home correct home directions from lines 3017 to 3019