Sound in my Cab DEAD!

I just purchased a 4 slot MVS cab for $100 and Im very happy with it. However, the sound would go in and out on it. I would have to jiggle the machine to get get the sound to come back on.

Well, now the sound is completly dead and I was wondering what could be the problem? Im thinking its some loose wires but Ive kinda checked them all and they seem to be fine.

PLEASE HELP!!

EXTREME NOVICE HERE!

Welcome FMINUS

The first thing to check is the 12 volt supply from the psu to the board. Without it, the board will run without sound.