Let’s check a few more things.
If you remove the large power plug with the blue cables from the C3D, and touch the L (Laser Fire) to the Gnd signals within that plug (use a short section of random wire to do this), does the laser fire? I know you already said that you put the factory board back in and it is firing the laser, but I would like to verify this.
If that works, please make sure that when you put the blue cable power plug back into the board that the cables are fully pushed into the plug. They like to get loose and not make contact with the mating connector on the board.
If this still does not fire the laser, I can walk you through an alternate wiring configuration that we have available. It will simply involve connecting the Gnd and L (Laser Fire) wires to other connectors on the board, as we have 3 different mechanisms available on the board to tell the laser to fire.
Ground will go to the board ground which is available via the top left screw terminal right pin (indicated with black arrow), and laser fire would go to “FET -” which is the lowest screw terminal pin along the left edge (indicated with orange arrow).