Help please.

I have a pair of Tower speakers ithink they are Beolab 6000, they have been great pairs up with my Beosound 3000..until recently 😞

 

One of the speakers no longer has an output. The working one has the  little greenlight at the bottom, the other, the light remains red.

 

I have swapped the wires, moved the switch underneath , and tried plugging them into the opposite connections on the beosound.

 

That is as far as my technical expertise extends.  Ideas anyone?

Thank you Angel.