Hi there,

I had exactly the same thing. It was on constant charge with the wireless adapter thing. I hadn’t turned it on for a while and was dead. Stupidly I didn’t report this to Sonos for around 6 months. By the time I did report it I was 2 days out of warranty!
 

Appalling customer support, no means of repair and no other option apart from “you could buy a new one”, why would you buy such a poor product again? This was my first Sonos product and will be my last. What a waste of money! Hardly used, scandalous!

A friend asked if I had a speaker they could use last week so I dusted off my Bose Mini Soundlink 2 that hasn’t been powered on for almost 3 years (I know as it was before I moved into my new apartment). It said it had 30% charge, worked straight away and lasted a whole evening on the 30% as well as charging fully the next day. Something Sonos should learn from, apparently Bose have some sort of battery protection in place for such things, Sonos… are you paying attention? 

Your sincerely,
One very nearly customer, who will never use you again!