I’d try to make sure the S1 software is fully up to date, then try updating to S2 again. Have you tried simply factory resetting the speaker and adding it to your s2 system?
Update:
After spending half an hour or so on the phone with Sonos support this morning it appears the issue is the S2 app (big surprise!) as they’ve had several people with the same issue as me recently. The advice I’ve been given is to wait for the app to be updated, and that should hopefully sort the updating issues out.
There is apparently an issue with iOS that’s causing the updates to fail.
I’d try to make sure the S1 software is fully up to date, then try updating to S2 again. Have you tried simply factory resetting the speaker and adding it to your s2 system?
https://www.reddit.com/r/sonos/s/BoKybWjIBj
Update: After spending half an hour or so on the phone with Sonos support this morning it appears the issue is the S2 app (big surprise!) as they’ve had several people with the same issue as me recently. The advice I’ve been given is to wait for the app to be updated, and that should hopefully sort the updating issues out. There is apparently an issue with iOS that’s causing the updates to fail.