By the way, I have tried to contact Sonos on “support@sonos.com”, however, this e-mail adress is no longer monitored.

And they have no live chat, nor any forms to be filled.

Do they have a customer support at all?? How can they be contacted?

It looks like there was a short inside the cable and you are lucky to have noticed this in time. Might be worth taking a look at the fuses/circuit breaker protection in place in the house because the breaker should have tripped.

ceo@sonos.com is the Sonos published address for writing to the man directly.

Thank you very much Kumar, I shall send e-mail to the CEO.

I doubt he will reply, but apparently, there are no other options.

Honestly, I would instead call Sonos Support directly to discuss it. As you point out, it is doubtful that the CEO would respond with anything more than a suggestion to handle it through more ‘normal’ means.

Seeing that it is a play 3 unit, it has to be quite old. And maybe over time, usage may have caused the internal insulation around the copper cores in the plug to fail, especially if there has been a lot of flexing of the cable at that end, something that can happen with any electrical appliance with some bad luck.

To repeat, if your circuit breakers did not trip, that should also be a concern.

To directly answer your question, no, I have not had this experience with either of my PLAY:3s. 
 

Looks like the crimping between wire and terminal has failed and eventually burnt out (due to high resistance).

The circuit breaker/ RCD would not have tripped as it hasn't shorted live to neutral and there is no earth in the cable.

Was it playing when the fault happened?.