Sonos One - only flashing white light, factory reset unsuccessful - any advice?

I seem to recall some threads in the past saying the reset button needs to be held for quite a while - possibly even longer than just when the LED starts flashing. Also for some older products they need to be connected by Ethernet cable during the reset process. 

Right - I had seen the same.  I have it connected to the network by Ethernet cable, and have held the reset button down for >5 min when plugging the power in, but none of it has made any difference in the gadget’s behavior, it just sits there with the pulsing white light no matter what.

You may be doing it correctly but just to be sure. You need to hold the play/pause button down before and after you plug it in.
When you turn on the power it will start flashing white, after a while (1-3min) it will start flashing orange. You can now release the button, after 2-10min it will flash green and ready to set up again.

Reset play 1. Solution found.

For the Sonos One units, I don’t think it’s the play/pause button.  It’s the bluetooth/connect button on the back above the ethernet jack.  It’s the only “real” button on the device.  The play/pause buttons on the top of the device are all soft / capacitive touch buttons where there really isn’t anything to hold down / press down.  I’ll try that soft button for grins, but I don’t think that’s it.

Holy crap.  That may have been it.  It is now flashing white and red, different behavior than it has ever shown before.  Maybe this is it.

Unfortunately, that didn’t fix it.  It stayed blinking white & red indefinitely.  That sequence means that an update failed, and it suggests rebooting to try and redo the update.  When doing so, it goes right back to just flashing white forever.

They offered 30% off a new one, if I shipped this broken one back to them at my expense.  We’re not buying another Sonos.