1 - 3 horas
My 20" iMac was having issues turning on or staying on for quite some time. It finally gave up the ghost when I was too busy with moving, buying a new house and raising a spirited toddler to even think about fixing it. I bought a new 27" (whoa) iMac and moved on. Later, when trying to figure out what to do with it I struck upon the genius idea of fixing it and giving it to my mother in law who is always having computer issues.
The repair went great. Ifixit was key in getting it right. I wish that some of the photos were coupled with a map of sorts highlighting the area of the computer I should be looking in. The recommended tools should be named "necessary tools" as some steps are impossible without them. The only disparity I had with the steps was #18 which said my Airport card should have two connectors but it only has one. I tried editing the guide but for some reason it didn't stick.
So, I ended up feeling like a genius after reassembling my iMac and successfully turning it on. Only a few hours later, while trying to show Mac basics to my mother in law whom would take the iMac home, I realized I was far from genius. I would now be on the line with her providing tech support for months if not years to come. And there is no iFixit guide for dealing with that mess.
Get all the necessary tools. Torx inserts will not always work - recessed screws in certain places mean you need a thin screwdriver style driver.