Went out this morning for an errand and the key-clicker wouldn't unlock the doors. When I manually unlocked and tried to crank the car, it was dead as a doornail. I don't know where to start as there were no prior symptoms. Recently (and still) there was very wet floorboard/carpet only on the driver's side. Flummoxed! And I'm not even sure how to find the battery (duh!). Help?