My Marshall Stanmore, one of the ones from that first batch years ago, also broke randomly after about a year, year and half of use. Bluetooth or aux-in just gave the tiniest faintest whisper of sound if you placed your ear up next to it, something was clearly busted, and the local speaker repair shop didn't know how to fix it.
If you were like me and held onto your speaker as a pretty paperweight, they now offer a fix! It's considered a free out-of-warranty repair, but you WILL have to pay for shipping both ways. Ended up costing me about $80USD total.
Go to: https://support.marshallheadphones.com/h...
and submit a repair request. You'll then have to answer some questions, and send a photo of the serial number to them, with which they will verify if it "qualifies" for a repair.
Then there are some specific instructions about how to pack and ship it to their repair center, and once the repair is done (about two weeks time for me) they will send you an invoice to pay for the return shipping.
I'm beyond glad I held onto it for the last 2.5 years now, just got it back and it is working and sounding beautifully!