I have the same problem on a 2 year old Stanmore. The warranty is 1 year and the Best Buy receipt is long gone anyway. Mine acts a little different in that the Bluetooth led stays on solid. It never blinks as in pairing mode and no devices see the speaker anymore. I contacted Marshall online and they offered an authorization number for UnitedRadio that would repair for free. I would be responsible for shipping back and forth. I've since decided to get a 20 dollar Bluetooth audio adapter from Amazon and attach to the RCA inputs on the Stanmore. This is working fine for me and I'll live with this for the time being. Still disappointed the 400 dollar Stanmore broke after 2 years.
John