What do I need to fix liquid damaged keys?

The time spent removing each key, inspecting and cleaning & then trying to clip them back (Especially the top row keys) without breaking them is a 50/50. You also have to disassemble the laptop to get to the underside of the keyboard to try to clean it up, then reassemble to test to see if any improvement was achieved isn't worth the time & hassle, replacing the keyboard is the quickest and best solution. It is a bit of a task but not impossible with a bit of patience & care. MacBook Air 13" Early 2017 Keyboard Replacement Some videos are on YouTube on cleaning Keys but note that keyboard versions do vary but the process is quite similar.