Q7180 died. The charger needs to see a load in order to put out voltage, and if Q7180 is dead it won't see a load. One way to confirm this is to cut off a good magsafe 85w cable and attach the ends to a DC power supply, set it to 18.5v, and use that as a charger. It won't care if it sees a load. See if you get any change in activity there.