So, I had read a few posts from various sites about how a problematic iSight (one that didn't show up in system profiler) could be possibly caused by a loose cable. The guides reported finding a loose connection in the iSight cable behind the bezel. They reported opening up their MBs and successfully getting behind there for the fix. I thought I'd be okay opening up my 15" MBP to see if my iSight dilemma could be cured in the same way. I used this guide: http://www.ifixit.com/Guide/Repair/...uo-Models-A1226-and-A1260-iSight-Cable/1314/1 to get to the cable. I did skip a number of steps immediately following the detachment of the bezel; going directly to the upper iSight area simply disconnecting and then reconnecting the cable. This seems OK because the guide is for replacing the entire cable itself; whereas I just wanted to check the top connection. Screwed everything back up, and, just my luck, my MBP does not start up. No lights, anything. So I've been trying to retrace everything and see where I could have gone wrong. Here's what the guide required to be "touched" or altered: 1. the trackpad/keyboard ribbon cable - seems fine, good shape, reconnected it carefully 2. Airport antenna cables - fastened back as they should, and would these really affect the MBP's ability to power up anyway? 3. the two ends of the iSight cable - see above 4. the inverter cable - not sure what this does, but was careful with wires and made sure to plug it back securely 5. data display cable - am thinking this COULD be a candidate for the problem, but I made sure to plug it back in tightly Can anyone point me in the right direction? Perhaps some troubleshooting tips for an MBP that does not turn on at all? What area here seems most vulnerable? ONE LAST NOTE: I do NOT have a working battery at hand, and so have only tried powering up from AC power (which shows a light when connected and is unharmed). I will try powering with a battery ASAP; however, I believe it should be able to boot up through AC power anyway. I realize this is a lengthy post but if anyone could take the time to assist me I would be so so grateful. Thanks.