Watch Hangs At Apple Logo Screen

I have been fighting this all day. Apple support chat couldn't help.

I have two of my three watches that will not restart past the Apple Logo screen. I have rebooted the phone several times. Toggled BT off and on endlessly. Forced restart of both watches at least 10 times by holding in the button and crown. Nothing works.

Sometimes the screen will blank off and come back to the logo, but no further.

I have unpaired the watches from the iPhone app. When they were paired, one of the "dead" watches did appear as connected on the iPhone settings Bluetooth screen.

I'm out of answers, short of taking the bloody things in to my local store, which will likely do no good. Anybody got an answer? Short of taking a hammer to them?