If a character uses Laser Turret and rolled a critical miss - what to do? no damage dealt at all ? what if a critical hit is made? 2 damage plus one damage?

The turret is actually making the attack so there is no damage to the figure and 1 damage doesn't do anything to an object so there is no effect for the laser turret crit missing on an attack.

Of course there is always the possibility of errata.

BoT

hmm I have been thinking that if the critical miss happens, that would mean that the Laser Turret would be backfiring....so thus, a damage should be applied to a character who used it. know what i mean? Laser overload boom....

Going strictly by the rules, BoT is correct. It's best not to apply to much logic to rules applications...dark and dangerous road there. The Turret is being given the action, so the turret takes the damage.