changed battery, now cannot turn off, why?

What part inside of the phone controls on/off? I changed my battery, and now cannot turn the phone off (the click button on the top right of phone does nothing). I am guessing that it has something to do with re-connecting ribbon #5 (this didn't look right when I was re-assembling)...but I thought I'd try things how I had them, then go back if necessary and find the ribbon cable. But now since my phone will not shut off....I don't think I CAN safely take it apart while turned on. Will I short something out if I try to take the phone apart while still powered on?