How can I repair my Bass Amp?

So I recently bought a Hartke LH500 bass amplifier and a GK410BLX cab along with it. Everything had been working fine until yesterday, now when I hook the amp up to the cab all I get is static noise which changes when I mess with the volume control on the amp. Does anyone have any advice or idea to what the problem would be? I was playing it yesterday, it worked fine, turned it off, went to go do something, came back and then this problem started. Thanks for any help guys. Also, it seems it might be a problem with the amp but I can't be positive.