Why is my Apple Watch not turning on after I just got it
Why is my Apple Watch not turning on after I just got it out of the box (it’s been charging for 3 hours)?
Apple Watch
See the 'Get help' section in:
If your Apple Watch won't charge or it won't turn on - Apple Support
If that doesn't help, I wouldn't fool around with it much more. Return it.
Returns & Refunds - Shopping Help - Apple
or if you still need help, contact Apple Support.