Please supply your testing gcode. It is important to enable laser mode with
M452
and then laser only turns on during G1 moves IF e increases or M3 was send. As asoon as line is finished laser will turn off, or it would make a damage waiting there.
And last of all it uses pin 2 so make sure that pin works to enable laser. You can test with
M42 P2 S255
and disable with
M42 P2 S0
But be careful it will be on constantly at same spot!