@cesther It always used to be the case that one could move any axis before it had been homed. This meant that there was nothing to stop a gantry being moved outside it's normal limits by accidentally entering a wrong value. This was deemed as being potentially dangerous by some users - especially OEM manufactures and CNC users. So the firmware was changed to prohibit any moves until an axis has been homed.
This is a safety feature but it can be overridden either by using an S2 parameter in a specific move command or by putting M564 H0 at the end of config.g as a more "global" setting.
Once an axis has been homed, then any movement command will stop at the minimum and maximum values that have been defined for that axis. So for example if your gantry was sitting at 10mm away from zero and sent a command to move it 100mm towards zero, it would only move 10mm and stop. But if you use M564 H0 then whenever you turn on the machine, there is nothing to stop it acting on a command that could send the print head trying to go beyond the axis limits and crashing into the frame or worse.
Personally, I do use M564 H0 but I am experienced enough to understand the risks which I accept.
