Thanks for sharing this! They even seem to ship internationally for about $3, that is really useful!

Indeed, executing the detachment process of the battery using "thumbs" is a highly risky operation only to be performed by well-trained thumb specialists. The use of other "fingers" is much more common, as it might induce fairly less risk of severe injuries or death. Also, "Fingers" have a sweet little picture illustrating the right tool to use. I changed the guide accordingly.

I haven’t bought a replacement key yet so I can’t guarantee this 100%, but I think, that these transparent “sockets” for the white butterfly mechanism are part of the key cap. So I’d guess: Yes, the transparent part is integrated in the replacement key.

If you buy one, I’d be happy if you’d let me know whether this is true! :)

When this is damaged, is it possible to replace the key so it functions as new?

It depends on what’s damaged. Most likely it’s not the key cap but the white butterfly mechanism itself. If you replace that it should work as new. But I recommend to try cleaning as in the instructions above first – for me and my friends keyboard issues with these models always came down to dirt in the mechanism.

In theory, the transparent clips shouldn’t really affect the function of the key. It rather holds the key cap in place, so if these are broken, it is more likely that your key caps don’t stay in place (e. g. are lifted up or slightly turned when typing).