What is this piece, what does it do, and how might I repair/replace it

So I recently bought some old consoles because why not. Some were broken and I figured I might be able to repair them. For my GBA SP here I heard rattling inside, which obviously isn't a good sign. I opened it up and found this. I don't know what this does, what it even is, or how to replace it if I have to, so I was hoping some people here could give me some help.

I also saw this little piece that I have no clue where it came from. I don't think its too important but a little help on figuring out what it is would be nice. Thank you.