Interior Lighting Issue

I have a 1995 Buick Skylark V6. One day, I believe I crossed a positive and negative cable while connecting my amp for my aftermarket radio and the interior lights went out. I originally thought I had blown a fuse, but upon inspection the fuses and fuse box panel all checked out. Radio still worked. The warning lights on the instrument panel would light up, the gauges would work, but they wouldn't light up at night so I need to use a separate light plugged into the cigarette lighter adapter in order to see the gauges at night. NO lights work inside the vehicle except the glove box light. I replaced the dimmer switch, replaced any bulbs that were blown in the instrument cluster, and even tested the fuse box panel which tested good as well. I am at a loss here, as I hate not being able to see in my car at night without a flash light, and hate not being able to see how fast I'm going or how much gas I have at night. Radio works fine, but nothing else does, including the climate control. Like I said the warning lights on the instrument cluster, like the seat belt light, battery lights and all those work, it just doesn't light up when the lights are on. Bought brand new dimmer switch and that didn't fix the problem. what gives!?