My Apple Watch ( Series 1 ) is still alive and working quite well. It lasts for 8-9 hours if I don't use the heart rate monitor, while doing sports. I think at this point I could say that my Apple Watch is not "all-day" battery life.
It's been worn every day (and charged every night) since it was purchased.
Battery has been fine for me. I wear it at night for sleep tracking, and charge it when I shower. Even on days when I shower once, I usually manage to get through the day without issue.
It lasted for two weeks and a half reading about 4 hours a day.
Sorry about your watch though, I'd be bummed too if that happened.
I took it to the Apple Store. They gave me a brand-new stainless steel Series 0. Apparently the battery swells sometimes, in the older watches, after a lot of use, and pops off the screen.
That's what I call customer service. That's the experience I get over, and over, and over again, from Apple. That's why I keep coming back.
Apple backs up its products.
Take your Watch in, and give it a try.