If you go to the first post in this topic, you will find a gcode you can download. Run this g-code file. It should work.
Another thing you can try is putting your display in Marlin mode. Hold down on the display knob for 3 seconds. In Marlin mode you can use the laser controls. You want to turn the laser off. This set the laser in manual mode where you can control the strength. When it is on, it can be controlled by an M3 or by inline commands.
It is likely that either both of these things will work, or neither of them will. If neither work, you will have to troubleshoot that you have the right pin and have the cable connected correctly. You will need a multmeter so you can test the voltage of the pin. An M3 or an M42 can be used to turn the pin on. If you need to test the pin, I can provide more details. You have to do it carefully so as to not short out the pin.
Edit: I don’t know how well “multimeter” translates, but I’m referring to something like this, and it doesn’t have to be an expensive one.