When having purchased the tracker recently at a local store , fastest to exchange at the store with receipt. On online stores in the account there can be a return / exchange option as well. If purchased from Fitbit.com , the support team can be contacted from the contact page . When contacting , best to share what you've already done to speed things up.
It's up to the store where purchased, or Fitbit support to decide how to help solving the issue regarding warranty.
Best Wishes
