It seems to me that if the connector opened it would just cause the music to stop without creating a problem for the amp (the current would just stop flowing). It the connector shorted, this could cause the amp to shut down, blow a fuse, etc. since it sees the short and reacts to protect itself. In any case, I'd return the cable to the mfg. and have them redo the bananas (or have someone do it locally). Shorts between amps and speakers are nothing to mess with.
Perhaps there was never a problem for the amplifier.
Nothing says that it shut off or went into protection mode.
The music just stopped.
The pop could have been just the pops and clicks of analog ( I get a lot of pops from static normally), accentuated out of the left channel to my ears because of the sudden DEAD silence from the right channel.
It seems odd the amplifier stopped working on the right, worked fine on the left, and then didn't work again when back to the right until I fidgeted with the speaker cable.
But in any event, you are right, the cable needs to be replaced.