Answer to: MacBook Air does not boot at all, fan spins up momentarilyBased on my experienced, this is what I do. I unplugged the battery, press Power Button for 10 secs and leave it for 24 hours to discharge the left over power in the logic board. The next day, don't plug the battery, plug the power charger and see if fan spins. If the fan spins, wait for few seconds until fan stops by itself then it will finally spin again booting with the chime. Let it finish loading, plug the battery back in, shut it down then screw back the bottom part.
Answer to: Replacing only the keyboard without full TopcaseYou can replace those rivets with those black tiny keyboard screws. Works for me. In fact, you can reuse those rivets again if you want, done it in Macbook Air. Apply cellophane tape before pulling the keyboard, so you can safe all those rivets.