Can’t connect phone to watch

I can't pair my iphone 7 with my apple watch 5. I unpaired them, as I could no longer make calls from my watch (it said that I didn't have the newest software - but when I checked my app, it said that everything was up to date). Now, I can’t pair them again. I’ve tried turning off both, turning off Bluetooth on my phone, deleting my watch from my phone's Bluetooth list. I’ve probably tried to pair them 20 times now. I even tried to pair the watch to my husband's phone, but didn’t succeed. Any ideas?