No sound on Lowrey Organ. Speakers work. Any ideas?

It is a Lowrey Premier organ. I got it a Goodwill a couple of days ago. It worked fine for the first day I had it. Then after my brother played on it, it no longer makes any sound when a key is pressed. I can still play the preset songs so the speakers work and the "split keyboard" selection setting still recognizes the key input. They key input does not work for setting the chords of the preset songs though.... I am pretty lost as to what to do. Any ideas as to what could be wrong? Plez help meh.

My brother was playing it a pretty loud, and was messing with the buttons kind of randomly. But the speakers still work fine and the reset button should negate any changes he could have made... right?