There is a concept in mechanical engineering where something can have a "normally closed position." You see this often with valves. The idea is that the normal

There is a concept in mechanical engineering where something can have a "normally closed position." You see this often with valves. The idea is that the normal resting position of the actuator prevents flow throw the valve. The effect is that the valve automatically shuts itself in the event of power loss or system failure. I presume they have implemented something similar. I might guess that the lasers may not be turned on if the system cannot somehow validate the integrity of the lens the lasers shine into. Same thing with the part that cuts or provides power to the laser. It's been a while since I studied circuits as a mechanical engineering undergrad, but I believe that you can also design circuits that behave in a similar fashion.