Think of a path that is supposed to be travelled all the way round: the current leaves the battery, goes through the lamp, and comes back. A short circuit is the moment something lets it jump straight across instead. The long way round is skipped, and whatever sat on that long way — the lamp, the motor — is simply passed over and left dead. Both meanings of the word live in that one picture: a route that was meant to be followed, and a jump that cuts it out.