Have you called Sonos Support to discuss it?

When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

There are several things that could be wrong, most of which this community can’t help with. I’d certainly double check the amount of power being supplied to the ‘stand’, but can’t help if it’s correct. 

Of course either the speaker, or the charger loop, could be faulty, but notwithstanding that, I have heard of people placing the charger-loop upside down or on a carpet where the ‘pile’ prevents contact and I have heard of the power pack tripping and needing to be removed from power for a couple of minutes to discharge and it then works again - check its cable too at both ends. If it’s none of those things then contacting Sonos Support is probably the next best step.

edit: consider trying a different power outlet too.

As ​@Ken_Griffiths says, first time I placed the charging base at the wrong side. And, of course, it never charged.

Take a look, the right side is obvious, but if you go fast could happen.