help car wont start

Hi, I recently installed some clear corners on my 95 525i and everything seemed to go smooth. Anyways later that day I was going to take my mom to the store when my car wouldnt start. Everything seemed to be ok battery worked, radio, lights would come on etc. It just didnt turn over or anything when I turned the key. It says "Brake LT circuit" on the dash and I checked the owners manual it says "Bulb or circuit defective" I did not really touch the light bulbs or anything electrical. The brake lights seem to come on. All the lights work etc. no blown fuzes in the fuze box, dont know about the big ones though. Any suggestions what happened and why it wont start?