Well, it happened yesterday. I had no hint it was about to suddenly go dead but it did. No matter that I have tried to do, the watch refuses to start up. I use the watch daily, which includes my brisk walking/jogging sessions and I only take it off at night for charging. I perspire a lot during the exercise sessions but no accidental damage, just normal day-to-day use. I called Apple Support, the person told me I will have to bring it in for servicing and if there is any signs of accidental damage, I may have to pay a service fee. Does perspiration damage the watch? May just get a Fitbit Blaze and use the Apple Watch as an occasional watch, though this was not the reason why I bought it in the first place.