break-away switch stuck

I would replace it, they are not that expensive. The smoke was probably the result of the switch trying to make contact and the fingers of the switch and they are probably rusted and/or corroded. (When you pull the pin the fingers inside of the switch spring back and try to contact each other). Disconnect the battery if you cannot put the pin back in temporally. If and when you replace the switch, do a monthly maintenance by pulling the pin and wiping it clean and reinstalling the pin. A little WD40 might help prevent it happening again.