Did you try cleaning the battery posts and clamps?
Also, how old is the battery? This happens all the time, esp. once it turns cold. A weak battery can go on and on, seemingly just fine, then one morning it just craps. This can even happen from the beginning of the day to the end. Happened to me just a few weeks ago. Went from asymptomatic to dead, wouldn't even light the dome lamp, in the course of a stop at a garage sale. The battery was six years old.