Removing the hard drive from a failed iBook 14" (A1007). The owner had contacted Applecare and they assured him the laptop was dead. It had recently had the logic board replaced and was not booting, looked like it was failing POST (no chimes). The owner wanted to remove the hard drive, mount it in a 2.5" caddy and transfer the data onto his other Mac.
I received it and noted how badly the Applecare guys had put back together the case (it felt sloppy around the edges). There was one of the rubber feet missing and the battery was the wrong colour.
I started to remove the hard drive, based on this guide, but checking at each stage whether the laptop booted. When I got to removing the Airport card, SODIMM and sheild, it booted. Woot. Narrowed the component down to the PCMCIA Airport card. There was a distinct whinny from the card area when the power button was pressed. Tried my own Airport card and it booted. Informed the owner and he's obviously delighted.
Makes me wonder why a failed PCMCIA card can cause a system not to boot. Answers on a postcard.