The fuel cut off switch cuts off fuel delivery in an impact. It has got a defined weight that is dislodged when experiencing certain g forces. All you need to do id press the button and the weight will be placed back in its original position.
the problem is that i had an accident with another car while in my punto but then, the lights was still on but then after a while all electric went dead so it seems the battery went, the car was a write off anyway.