every light on the dash started to flicker

I have a 2002 Saturn sl I was putting in a new stereo and when I connected the power wires there was a spark. After the spark I turned the key to see if it had power. When I turned the key to run every light on the dash started to flicker. I started the car after this and it ran for a second then died. Now the car will turn over but not start. Also the interior lights no longer work the sun roof still works but all the lights won't turn on. I have checked all the fuses and the battery is good what should I look at now?