> been told by Sonos support that there's no way to stop the countdown, forcing them to buy new devices after 21 days
> you can't recover it if you're good with JTAG, because it's blacklisted as "recycled" on their servers. There's nothing stopping these things from working except Sonos says they can't.
These two points are not compatible with each other. If the only effect of recycle mode is that the device gets blacklisted on a Sonos server, then Sonos is trivially able to undo the effects.
They're perfectly compatible with each other. Sonos can stop the countdown, but won't.
You should of course be cautious about assuming a cursory look from a 3rd party is enough to know for certain how the device is bricked, but it's not abnormal or weird for a business like Sonos to use a half-baked technical strategy to brick their devices, and then to just stonewall anyone who calls into support.
Half of the time that a company says, "there's no way for us to do X", what they really mean is, "please go away now."
> you can't recover it if you're good with JTAG, because it's blacklisted as "recycled" on their servers. There's nothing stopping these things from working except Sonos says they can't.
These two points are not compatible with each other. If the only effect of recycle mode is that the device gets blacklisted on a Sonos server, then Sonos is trivially able to undo the effects.