Not normally that fast nor that complete. That sounds a lot more like a wiring issue which could easily kill all power. I guess conceivably, a connection could have broken inside the battery to get your symptoms but I've never seen it before. Have you tested the dead battery (ideally loaded but at least voltage)?There's a new battery for the killer sitting on the bench.
Old battery was 5 years. It shared a battery tender with 2 other bikes. Never had a blip. About a week ago I'm out riding. Made a couple stops everything fine. Make another stop and 15 minutes later the neutral light won't even illuminate. Not even a hint of a glow.
Is the death of a battery often so sudden?
It was a sealed maint free KMG from Kapscomoto. So is the new one.