dead casio sa-9?

[dimefan90]

i was adding a deep crash button and high pass filter to my sa-9 and it has died. it turns on but none of the keys or buttons work. when i turn it on and switch on the feedback mod, it screams like a bitch so there is power. plus the knob for the voltage drop also controls the feedback and makes some crazy noises. if i didnt want to use it as a actual keyboard it would be quite cool.

i thought i might have bridged a couple of pins on the IC but i got all of the solder out.

any ideas what could be wrong. this thing is irreplaceable to me.