Watch

That's not good. What kind of charging plug are you using? Can you try a different charging plug or if you have USB C input on your computer, try that? Have you already paired it with your iPhone?

You could try a Forced Restart, which is to hold BOTH the digital crown and elongated power buttons in at the SAME time until you see the Apple Logo, then sign into the watch when prompted and try to charge again.

If, after that, it still won't charge, you'll need to reach out to whoever you purchased the watch from.

Brand new to you or brand new from Apple or from someone else?

If brand new in a sealed box, did you remove the white sheet over the battery charging puck before trying to charge the watch?