I need help. I changed the alternator today. I removed the battery cable and changed the alternator without a problem. I was tightening up the battery cable and dropped the ratchet and it touched both the positive and negative terminals only giving a quick spark. The vehicle won't crank. It sounds like it tries to crank when you turn the key over with your foot off the brake. When you press the brake you get nothing. Whether the brake is pressed or not the windows do not power, and neither do the power locks or exterior lights. I have since changed the battery as it needed changing anyway, but any advice where to start would be great.