Hi, Same thing happened to me, and now my Apple Watch which is just over two years old is totally bricked. When it started losing it's charge rapidly, I made an appointment to visit Genius bar for a battery servicing (it was showing a health of 78%), but then cancelled it at the last minute, as I thought it may be worth trying to reinstall iOS on my iPhone (this was based on some advice given in Apple and other forums). Then, 5 days later, I woke up with the watch on the charger, and it wouldn't turn on - nothing doing, tried all restart methods. So I made an appointment and went to the Genius bar, and after being made to wait almost half an hour, they took it for a check. Told me nothing doing, my only option was to pay for a like-for-like replacement at a cost of $420 SGD (about 310 USD). I was shocked by this, considering it's only slightly less than the cost an Apple Watch Series 9. I urged them to replace the battery which I was willing to pay for, and they said they can't do it if the watch doesn't start up. Crazy! If your watch is still draining fast, you'd better get the battery serviced before it becomes a useless brick! Really feel cheated by Apple, they have lost me as a customer after 20 years of custom.