Watch battery

Batteries degrade over time and while it may suddenly seem rather odd, that’s simply how it works.

Watch Battery Replacement:

Current Apple Prices:

• No charge for in-warranty or AppleCare+ plan.

Out of Warranty Prices:

• All Eligible Watches: $79 U.S. Dollars.

➢ Check AppleCare Coverage.

Click ▶︎ Apple Watch Battery Replacement.

See this link and follow the instructions provided

If your Apple Watch won't charge or it won't turn on - Apple Support