Hi,

Have you tried unplugging the USB cable out of the power adapter, then connecting the cable into a USB port of a turned on PC? (the speaker is connected to a PC via the USB cable to see if it charges)

If it starts to charge you have a faulty power adapter.

If it doesn't, try a different micro USB to USB cable and see if it charges now.

If it does you have a faulty USB cable. Try the working USB cable with your power adapter to check if the power adapter is OK.

If it still doesn't charge, you either have a faulty charging circuit or a faulty battery in the speaker.