Apple watch 8 won’t charge

See -> If your Apple Watch won't charge or won't turn on

If your Apple Watch won't charge or won't turn on – Apple Support (UK)

• If you still need help, contact Apple Support.

Are you using a proper Apple USB-C charge brick of at least 10 Watts?

The article If your Apple Watch won't charge or it won't turn on - Apple Support including the advice to Force Restart near the end of the article 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. Or Genius Bar Reservation and Apple Support Options - Apple

 (Note that recent Watches without plastic protective packaging do not usually have film over the watch back or charging puck).