I have 2 Sonos One SL speakers that were on a system at my office and now I have moved them to my house. I have tried the factory reset directions 5 times on this link below on each speaker…
https://support.sonos.com/s/article/1096?language=en_US
The light just slowly flashes white - never amber - then goes to solid white, then a few fast orange / red flashes then white again.