If you cannot factory reset the device using documented steps then
unfortunately you'll probably need to replace the device as there's no
way to update the system firmware or OS when it's in this state. I would
suggest you contact Google Support and ...
FYI - I got in touch with someone from Google Support today. They
confirmed that the recent OS update has bricked hub devices with certain
firmware revisions. They've been flooded with similar calls from other
customers with this exact same problem.I...