Your Apple Watch is under warranty.
Take it to an Apple Store or Authorized Apple Service Center for diagnosis and advice how to proceed.
If you do go to an Apple Store, find the store here:
http://www.apple.com/retail/storelist/
... and click the store's link to make a Genius Bar appointment. That will save you waiting time once you arrive at the store, and you can pre-alert a genius why you are visiting.