i have the same computer and i am getting a 1962:no operating system found. I opened it up and found this white wire is broken, i copied your picture and circled the little white wire on the bottom front, in this picture it looks like it goes to the hard drive, but i dont see a place where it wold connect. any help would be appreciated!!
http://postimg.org/image/rmk4825if/3196a443/[/img]
http://postimg.org/image/rmk4825if/3196a443/[/img]