How I saved my daughters MacBook Pro filled with nail polish remover
My daughter spilled a lot of nail polish remover into her MacBook Pro keyboard, making it turn off immediately. Hereafter she used a hair dryer to dry it, melting 3 keyboard buttons.
The Mac would not boot hereafter, and the disk tool could not format any of 3 disks I tried. I made a full hardware test on the Mac, finding no problems. I tested the hard disk in an USB enclosure, and it worked fine.
Using Google I found out, that many people have solved this kind of problem by changing the SATA cable. Even though I find the price for this SATA cable extremely high, I decided to buy it to find out, if the Mac should end as spare parts, or could be used again.
The repair is extremely easy. Remove the bottom plate, remove a few screws, and the hard disk and cable can be removed. Mount the new SATA cable and the disk, and refit the bottom plate. I think it took less than 10 minutes.
After power on, the disk could be formatted. I then connected to my WiFi, and restored it from my TimeCapsule backup. It has been working perfectly ever after :-)
I have nothing to add to iFixit's adequate guide. I believe changing the SATA cable is one of the easiest tasks to perform. And the $100 is a good price to regain a MacBook Pro, even though I find it very pricy.