Recovering from a stupid blunder...
I was swapping out my 500 GB hard drive for a 1TB hard drive when my fingers slipped holding the old drive, it rotated outward and down. I didn't think anything of it at the time, but after reassembly, the machine wouldn't boot and no bootable drives were found...opened it up again and found that my cable had torn, ever so slightly. After cursing and screaming at my fumbling fingers, I went straight to ifixit and ordered a replacement drive cable (and a spare).
Following the online directions and installing the cable was a snap as I had also purchased the proprietary 5-point driver to remove the battery (now I am set for when my battery tanks in a year or so). Completed install, used SuperDuper to copy 500 GB to new 1 TB drive, had a big stretch and then rebooted...whamo! All functioning perfectly. Thanks ifixit!
Macs are so well designed that nearly all fundamental hardware failure modes can be handled by the modestly competent home user....done slowly, with ifixit's directions and making sure you have any special tools.