New apple watch pairs and then unparis

I bought a new apple SE watch. I had an old series 2 or 3 watch already.

When I try to pair the new watch it pairs then unpairs. I've turned both on and off (phone and watch). i unpaired the other watch - even though I don't think I needed to do that. I've updated my iphone software to 15.7. I'm about ready to return it for a refund, but hopefully I can get it set up with a little help. I didn't purchase the apple care plan cause I never needed a plan with the other watch. Any other suggestions?