unable to pair watch to new phone but not paired with old phone either

I just upgraded my phone, giving the old one to my son. I didn't not go through the unpairing process on the old phone, just had him delete the app from his phone. I tried to pair it to my new phone but the screen still looks like it is paired with a phone. I downloaded the watch app back onto my son's phone but now that shows that the watch isn't paired to that phone either - it isn't paired to any phone and yet it's not giving me a blank screen so that I can pair it to any phone. Both phone screens tell me to start pairing but the watch is not in pairing mode. How do I fix this?