Why won't my speaker turn on or charge?

My speaker stopped working 2 days after the ending of its warranty unluckily.

It doesn't charge nor turn on when plugged in, I tried the quick solutions advised on this website without opening it.

The only thing it did was being recognised by the computer through USB, and installed the software to use it though it did not appear on the list of connected devices.

If I open it, what do you think I should try to identify the cause and then repair it?

Thank you!