I dropped my car off to get a FP change. I get my car back and now the car has no audio. I have a 1200w kicker amp installed along with the factory amp, and 10" kicker sub installed that was working perfectly fine prior. I took it back to them and they did a quick look and couldnt come up with anything. and am taking it back tomorrow for them to have more time. Weird thing is, i kept hitting the power on and power off to the radio and it actually came on and worked. But i turned the car off and back on and now its not working again. Everytime I turn the radio on i just get a low constant hum from my sub.

I've tried only stuff i know about:
disconnecting and reconnecting the battery.
Checking any fuses related to the audio
Ran the radio in diagnostic mode
I got 2/4 that say good. P1C6 says CHEC and so does N050 but the others are fine.