Imac 24" issues

Question

Hi all,
I recently inherited an imac 24" 2008 model, the only catch being that the original owner removed the hard drive, no problem I thought....  After receiving the imac and plugging it in, the unit started, fans immedialy activate and fun full power, and the screen starts in a yellow colour heavily pixalated in what i can only describe as a 70s looking wall paper patten.
I removed the screen, and inserted a new 1tb sata drive, from a previous windows pc (installed with windows etc), and checked that all of the temp sensors were in place again, after trying the unit again, same result, and it will not respond to any keyboard commands, or perhaps it does and I just cant see it...  sometimes the apple log pops up over the 70s wallpaper, not always....
I have a usb drive, formatted guid, complete with the installESD file (downloaded from apple store via my macbook), and iam trying to install osx onto the harddrive (fat 32 installed with windows at the mo).. if i boot the unit pressing option command (boot order right?) nothing happens....  (on a win keyboard it should be the windows key and Alt correct)
Ive toyed with the idea of purchasing osx on dvd and trying that way, but i guess that would also require the boot order to be changed?
Any ideas here would be a big fat help, as you probebly realise I am not very experience with mac, and the whole idea of not having a bios just freaks me out
Thanks!!

Answer 1

In my experience, Apple's techs are generally very competent. If they say it's a hardware problem, it almost always is. The reason the repairs are so expensive is it isn't very practical to repair the multilayer printed circuit boards used in all modern computers so the only viable alternative is to replace the whole board, at least if you are going to guarantee your work.
Also, having opened up a lot of Macs & other similar gear, I know how easy it is to damage circuit boards & other components if you aren't careful. Just mixing up a few screws & putting a too long one in the wrong place can short out something it contacts, blowing out the whole board. Tiny surface mount components are easy to knock off the board with just a bump in the wrong place & it's hard to even notice the part is missing. Clearances are so tight in some areas that unless cables are rerouted exactly as they ran originally they can be damaged during reassembly.
When I tear down this kind of gear, I take lots of closeup pictures to use as references for reassembly & keep careful track of where each screw & fastener goes. And I never apply power unless everything is either back in place, firmly screwed down, or for a few items I have added an improvised ground path if they are going to dangle free. And of course, I follow all the usual anti-static handling precautions, including using a conductive mat to place assemblies on if they are removed from the device.
Hopefully, your friend was careful when he removed the HD; if not, your problem easily could be a hardware one.