I would say that on the second pic, there should be a connection between the second and third bright green bar.
Besides that, the black thing is probably a resistor (cheap laser?), so to "mod" it, you would have to unsolder that and solder one with lower resistance or a potentiometer in ints place.
Good luck with cramming an smd-poti into that thing and soldering it...
But if you want to know how it works, read here: spring connects to battery and switch, and the switch shorts bars 1 and 2 on the bottom picture. Then the current "hops" from bar 2 to bar 3, runs through the resistor(?), and changes the side of the board at that little hole. There it goes through that apparently metal bar, through the diode (creating laserlight in the process) and leaves it through the diode casing.
If you want to mod it, your best bet would be an external solution, or a new casing.