When replacing my hazard switch the other day, I had some trouble pulling out the radio unit. Turns out I missed two screws (argh! I re-read the instructions so many times last night). Finished the job today, but I have no response from any of the radio unit. Since it was left on, I know it still works and I can control it from the steering wheel. But none of the buttons on the unit itself work. I assumed I lost a cord or wiggled one loose. There is one missing slot in the back, should there be something here (if so, I can't find it anywhere)?! Otherwise, can you give me some instruction on how to get those middle two out so I can try unplugging and replugging them all in? Or could there be something else that's causing those buttons to be unresponsive...