My iMac which I own for almost 5 years went dead during a power surge. After spending some time online I suspected that it needed a new power supply, and your site was most helpful.
The repair went very well. The instructions were clear and easy to follow. It took me about 2 hours to have it fixed.
It's important to have all required tools. It saves a lot of time. When attaching the screen back, put the four screws back into the holes first.