I recently purchased a used cyber deluxe pr444 . I had tested the amp with a guitar and it worked fine. I brought it home and now cant get any sound from it. It is getting some kind of signal because I can hear the guitar through headphones when plugged is to the back of the amp. Im sure that I am missing something simple here but I cant find any info from the manual. I havent seen any error codes either. Any suggestions? Your help would be greatly appreciated. Thanks!