The lock cylinder has Nothing to do with your radio or dash lights.....what about your AC control head? Does that light up?
Have you tried your dimmer switch? Is it possible it is turned all the way down?
At night, with the lights on, car running, if you move the dimmer switch from low to high, does your dash and radio AND ac control head respond? Or is it just the dash and radio that doesn't?
If all three do not light, what does your radio do in the day time......does it light up with the time, when not on? If it gives the time in daylight, and radio stations in daylight, but doesn't light at night, even when moving the dimmer switch, then you have a dimmer switch problem....not sure if that is all part of the headlight switch....