ALARM:2 means you’re sending something out of bounds and the machine has stopped you. Chances are you’re trying to use ‘Current Position’ or ‘User Origin’ mode, but don’t know what those mean. Change to ‘Absolute Coords’ and read here to understand the different modes and how they work: https://lightburnsoftware.github.io/NewDocs/CoordinatesOrigin.html
Yes, the machine homes itself, have moved the head to another corner and started and it return to upper left corner. I don’t understand what you mean bump of it?
‘Homing’ is the process of the machine moving the head toward one end of one or more of the axis until it hits a switch. It uses that to find the end of that axis, so it knows where it is. The “bump off it” means that once it gets to the switch and engages it, it backs off a little until the switch releases.