If not done already, perhaps try a different power outlet, cable and/or fuse as appropriate, if still no LED or signs of life and you’ve tried a factory reset, then it’s best to get in touch with Sonos Support via this LINK.

Thanks brub for the advise. 

Update: it’s dead. Waiting for the quote from local dealer. Last for only 28-29weeks . Extreme disappointed. And yet I was doing so much research between Bose & Sonos. Now just hoping for a comforting recovery plan from the dealer if not I’m getting rid of all the speakers . Life span is way too short .

Sorry to hear that news I guess these things can happen to any device/any electronics brand/at anytime - it’s sometimes a case of c’est la vie. I certainly would be upset too, but I don’t think I would then go onto cut off my nose to spite my face by getting rid of all speakers, instead I would personally take up any trade-up offer and buy another Sub (in addition to getting the original Sub repaired) and with any money saved through the trade-up, perhaps take out small appliance insurance to then cover any breakdowns outside the of the warranty period. You may get cover that includes cover for all your other speakers aswell if you have held onto their proof of purchase.

Anyhow sorry to hear the news and I hope the local dealer is able to fix it for you at a reasonable price point.