I spilled wine on my laptop keyboard. It worked fine initially, but by the next morning, keys would not function and it became impossible to use. Not wanting to buy a new machine or send off the computer to Apple for an expensive repair, I bought the parts and tools straight from iFixit. I found out I had to do an upper case replacement, likely the most involved repair you can do.
After retrieving my package from the post office, (can iFixit figure out a way to allow the customer to waive the signature requirement?), I sat down with some paper to hold the screws and parts and another computer dialed into the iFixit manual.
Anytime a screw or piece came out, I drew a circle on the piece of paper, labeled it with the step in the iFixit manual and proceeded to take out nearly every single part of my machine to replace the keyboard. The steps were easy to follow and I read all the information in each step twice before I proceeded with anything. This was important as, for example, removing the display cable from the logic board incorrectly would have ruined my machine.
Everything went well and I found only one small oversight in the directions. In the final step, when swapping out the old and now empty upper case for the new one, a support bar that runs across the middle of the case had also to be removed and installed in the new case, but this was not mentioned in the repair.
In any case, the repair went just fine and I stepped backward through all the steps and reassembled my machine, which started up immediately and functioned perfectly!
Don't blow dust of parts if you have a bunch of screws sitting on a piece of paper next to your machine. I did so once, basically cleaning out some accumulated dust in the cooling fans, but accidentally moved my piece of paper where I was storing screws...luckily only one or two moved a bit, but I could have really lost them or at least gotten them jumbled together.