I defeated the Sparkmaster without using the switches or the controller. Had my strongest character go into sneak mode and move the oil barrel on the right side to center first then had my ranger hit it. Spread out my group in sneak mode so they weren't too close to each other in case of electrical attack; hit the mages charging it hard with spells, arrows and grenades to kill them off and used stun and knockdown on the robot to limit its attacks. The three wannabes died because they ran up to it but none of my party died and none of them got below 40% health during the fight. Oh yeah, a summon or two will keep him focused on them instead of yourr party.
