I think you should go back. I think it is a power amp failure. The led is only for the power supply. Perhaps the system has a thermal failure.
Is the unit hot / I mean can you feel extremely hot temperatures on the back? If you can feel it, can you compare it with the speaker that keeps working? Is there a thermal difference?
But for now I think there is an internal power failure to the main amplifier, this because you spoke about loud pops... Which normally only can be heard by older amps with no slow start......
Advice: back to the store