How do I get my Watch to move past the Apple logo after a force restart?

My Apple Watch 3 series was stuck in the middle of the OS8.7.1 software update for 2 days, so I tried to restart both the Watch and the iPhone. The phone restarted fine but the update was still stuck at the “downloading to watch” stage. Apple Watch would not restart, so I kept pushing buttons and inadvertently did a “force restart”. Now the Watch has been displaying the Apple logo for hours. How can I get my Watch to work again?