Basic check - are all the plugs at the bottom of the board plugged in?
It sounds like the speakers are wired correctly, but there may be a break in the wire. Have you tried jumping directly from one speaker to another with a pair of 'gator clips?
...well, there are two channels, but the left and right speakers should be the same one, with the other being the sub. I'm not sure how you can hook up a working speaker like that and not have it make noise. Can I get a pic of the back of the speakers?
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