Unable to Pair my Apple Watch

I've been unable to pair my Series 1 apple watch ever since I got a new iPhone 11. Every time I try to connect, I am told to update the apple watch software, even though it is already updated to 5.3.8. There is no button to further proceed (only a "cancel" button) after checking if my software is up to date. My only option from there is to "exit and reset watch" after which my phone unpairs from my apple watch. I was unable to disconnect my apple watch from my old iPhone before trading it into the Apple store, so I'm wondering whether that has to do with the issue. I already tried turning on & off my phone and my apple watch as well as resetting factory settings, with no help.

I've been trying to call Apple Support, but for some reason the call gets disconnected every time.

Please help me solve this issue. Thank you. Screenshots are attached.