Series 1 apple watch pairing keeps failing

I came across my old series 1 Apple Watch and I erased all content on the watch and am tried pairing with my iPhone several times. I have tried the camera pairing method which just continues on and on until the iPhone quits trying to pair. When I try the manual method the phone can connect with the watch but asks for a 6 digit code that “is displayed on the watch” but no code ever shows up.