Update: The contact is STILL dirty, however, it's attached to the board. Is it safe to take off, and if not, where do I go from here?

Bump, I really need this thing fixed! (I'll solder if I must, I have High Quality equipment)

I used ECG Industrial Flux Remover (A type of industrial contact cleaner, designed for sensitive electronics) after rubbing alcohol didn't work.

You said the board was cleaned good? What did you yse to clean it. The only thing I can think of is you have a short on that contact maybe by some kind of grime

lol

Hello everyone! I've been having a bit of a problem w/ my 3DS. I recently had to replace the screen and audio flex cable in it, and after I finished, the B button stopped responding. I've made sure all the connections are in properly, just in case it had something to do with the replacement, I've cleaned the board and the button, however, I haven't been able to find any way of removing the top contact for further cleaning. All of the other buttons work correctly. Something I've noticed, though, is if I play a game, such as Pokemon (don't judge me) with a B-button mechanic (running, etc.) it is stuck ON, not off. The 3DS is way out of warranty, as well. Any help is appreciated.