what can I do to get it start it?
Hello and welcome to Apple Support Communities, camilamarmol.
If we understand your post correctly, you're unable to update your Apple Watch. We’d like to help.
Since you've already updated your iPhone and reset both devices we'd recommend contacting Apple Support directly. You can do that here:
Thanks for using the Apple Support Communities.
My Apple Watch series 3 won't update and when it pairs with my iPhone 7 it stays in "finish set up on iPhone" But it never finishes and when I do all the updates in my iPhone and says the same in the Apple Watch. I already reset the two items
