I run an architectural woodwork shop. My MacBook Pro is subject to the worst conditions, including (but not limited to) severe sawdust inhalation, extremes of heat and cold, abusive handling and an impact from a brick, but it still keeps going. Until it needed a new i/o board. I found your site, downloaded and printed the instructions, bought the board, then sat on it for six months (ouch!). Finally, after the fans started to quit and garned such comments as "Hey, I didn't know Macs were powered by a chain and sprocket drive!" I finally decided to go in.
I followed the instructions methodically, taping the screws to their locations in the instructions I printed. I figured as long as I was in there I would take the fans apart, clean them and lubricate the shafts. I found clots of fuzz and sawdust in the vents and around the fans. The boards were all the color of a brown paper bag. I blew out everything carefully, then put it all back together, and with some trepidation, hit the on button. Nothing. Uh, oh. I totally f--ked myself, I thought. Then I remembered that maybe I didn't hook up the cable from the keyboard to the main circuitboard. I took it all apart again, and sure enough! That thing connects the on/off switch, duh! This time I was successful. The initial repair took me a very careful 1-1/2 hours, the re-do about 1/2 hour. To heck with woodworking, I'm gonna make a fortune fixing old Macs!
Just the usual-don't force anything. Like my top end woodworking machinery, this stuff is well built. You don't need a mallet to make an adjustment, but you do need your brain, a gentle touch, concentration, and to pay close attention to the additional comments. Oh yeah, and don't drop a brick on your computer. It kinda messes up part of the screen. I'll fix that another time.