Symptoms: device powers up, but doesn’t show on either network and refuses to factory reset. LED remains white no matter what.
I have cracked it open following this teardown https://www.reddit.com/r/sonos/comments/1zf9n9/sonos_playbar_teardown/ but nothing obvious stands out. The power supply is fine, based on everything I can see.
I am aware of wifi card failure, but I assume when that fails the wired network will still work, and that factory reset should also be available.
By the way, these things contain some serious mechanical engineering. Respect. And also they were a bargain in their day.