My Watch 7 Black Out..

Apple watch will not turn on or charge 

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

is the best resource for this situation. If you've completed that troubleshooting and the issue is still not resolved, use the link in the article to Contact Support. 

If you've completed that troubleshooting and the issue is still not resolved, use the link in the article to Contact Support. 

or Genius bar 

Genius Bar Reservation and Apple Support Options - Apple 

and/or 

Apple Support