For those that have come across the HomePod being bricked during OS update, there is a path forward but it takes talking to the right person.
My first gen HomePod got the blinking light brick up death back in September when OS17 updates were pushed out. Its seems like all the people that have reported this issue in the past had their device pair to an AppleTv, as mine was.
After coming to roadblocks with apple support via chat, retail store, and retail store management, I was told to reach out to phone support and ask for tier 2 support. I did that, but it wasn’t necessary to speak to a higher priority support staff. I explained the situation and I was told that apple can do software restores for out of warranty devices, but if it was hardware issue I would be on my own. I was sent a box overnighted and I shipped it back overnight. Within 3 hours of them receiving my bricked HomePod I got a notification that a replacement was being sent. I got it the next day. The device I received was a refurb and was running OS14 still. After a long update process, it is now running 17.
So if you are having the flashing volume light bricking issue after an attempt to update firmware, go down this path. If you get push back, try calling again until you find someone that can help you.