2004 Lancer Es Help!

Hello, guys, I'm a long time visitor of these forums who just recently registered. Anyways, I seem to have a problem with my 2004 ES. After installing an aftermarket head unit, I noticed a lot of lighting problems. For one, the becklight behind the AC nobs (all three which illuminate the nobs) no longer light up. In addition, my spedometer, rpm, etc are all significantly dimmed and the lights that light up park, reverse, neutral, drive, etc. also no longer light up. Finally my right rear light no longer lights up. I am stunned that installing an aftermarket head unit caused all these problems, but I don't think that all these lights just coincidentally burned out at the same time. Any help is greatly appreciated and thank you for your time.