I just got the update and it bricked my PW2. I have a black screen with a bluetooth symbol at the bottom with a line through it. Back button doesn't do anything at all. No swipe up or down. Swipe to the side just says long press to add a tile. I can hold down the crown button a get a reboot/shutdown/emergency screen, but reboot/shutdown didn't help.
** UPDATE **
How to Troubleshoot your Google Pixel Watch If your Pixel Watch won’t turn on or becomes unresponsive, you may need to restart or reset your watch.
support.google.com
I had to end up using the Fastboot option to factory reset my watch. Then I selected the Reboot Now option and when my watch booted back up it auto-magically found my watch and started the pairing sequence.