Repairing sanford home theater

I have 1 sanford 5.1 home theater. Any sound not comming from that. Power and all function are working. Problem is sound not coming. I already changed 1 IC. Now very big sound coming from the speaker. Like brrrrrrrrr..
How can repair that?

What the poll has to do with all this?

What was you reason for changing the IC, when that likely was not the problem?