i think the switch you mean is the door switch that tells the system the drive door is shut and ready to read discs ,if the laser goes up and down fires but dont spin the motor is shot
there is a sequence that happens just like any laser assembly for drives,just dont remember the sequence it goes through at the moment
EDIT: since you say the laser fires ,id say the motor is shot as it dont spin the disc up to speed..but,the laser firing just means its firing,the head adjusts up or down as a focus is one of the checks i think before the motor is turned on by the controller,could be wrong as i dont remember the exact sequence