Chosen Solution
I was attempting to fix a keycap for a MacBook Pro 2019 because it basically fell off due to the plastic white-tan color outer part being broken. However in result of trying to replace the key cap I pulled off the clear plastic part (which contains the dome switch) and noticed it had some kind of adhesive used to keep it attached to the keyboard. What would be a safe adhesive for this? I was looking at this but idk if it expands or would damage any of the other parts. Photos of what I’m trying to describe:
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Liquid thin super glue - think something like the small bottles from China that are cheap, or even the large bottles as long as it’s thin (most of it from China is). WARNING: Be prepared to replace the entire palmrest if you get it wrong! It will not be cheap! I’ve super glued domes on older Dells before that have fallen off due to degraded adhesive, but these are based on old designs where it is modular and I can cheaply replace it with a used OEM or clone if you mess up so it’s not a expensive mistake. While it tends to work in most situations, need to be precise and make sure to remove the scissor hinge so you can work without as much risk.
So if you mess up, which you will! You’ll need to pay for a new uppercase (aprox $1,000 USD) or what I would do is replace the broken parts which is a lot cheaper! As we can’t see what broke (post a picture or two) Adding images to an existing question I can’t tell you if that’s possible here. One source for KeyCap parts MacBook Pro Late 2019 - 2020 Click on the image of your version.
