Lily 2 keeps "shutting" down when plenty of battery exists.

I've had this. Lily for exactly 385 days and the last week or so it began having this problem where it would shut down like the battery was dead. When I could I would go plug it in and see that the battery was there. At times I would take it off and let it play out the rest of the battery or until it shut down on me again. Then I let it fully recharge out to see if that would make a difference, it has not. I can't use the watch without it being plugged in. It is no good. Please assist. This was more expensive than other alternatives but I thought Garmin was a good product and was willing to pay it. Show me I was right.