Thanks kitsch, this was helpful and informative

I'm fine with that

Well since your problem is solved, a little hijacking is in order...

I don't think I'd have to rinse it after spraying with electronic contact cleaner, since the stuff evaporates and doesn't leave any residue.

I finally got my Gameboy open, and...

Looking from the back of the Gameboy, I have to adjust the battery farthest to the right in order for the Gameboy to power on. That's the only one that has problems. Looking at the contact from the inside, it looks pretty horrible. Is it dangerous to get vinegar on the PCB?

There're also other points of corrosion, and my speaker doesn't get as loud as it should.

Other than that, it seems to function fine other than some vertical lines. Headphones jack works,
buttons, and everything else.

After I closed it back up I found what appears to be a tiny green piece of the PCB sticking to the side of my Gameboy. It has the number "6" on it. >_>

if you were wanting soldering tutorial, this is a really great resource: http://store.curiousinventor.com/guides/How_to_Solder

I cant get you a link right now, but nonfinite has a pretty good tut.

Oh. Open the Gameboy and take the contacts out so you can rinse them afterwards. Obviously that's more work if the problem is with the one of the contacts that are connected to the motherboard, but I've found that in most cases people have apparently stored 'boys in a position that makes the battery acid run down to the bottom contacts only.

Yeah. I actually have used the contact cleaner spray to clean battery contacts in a few things, including my Gameboy. It worked, but I also got the stuff all inside the system with my indiscriminate spraying. I don't think it hurt anything, though, since that's what it's designed for?

I just find it interesting that nobody ever mentions contact cleaner here. it's convenient to be able to spray it into hard to reach places, especially with the straw extension. But I guess that's not really needed in most game system modding applications, especially with cheap vinegar and alcohol available.

There's only one way to find out, right?

Would contact cleaner spray work just as well? I bought some at radio shack some years ago to clean my guitar's pots, but I never hear anybody mention that stuff on this forum as a solution for anything ever.

Yay! Excellent to hear. I remember the first time I did it, I couldn't believe how easy it was to fix something a lot of people would simply throw away. Then I went around fixing everything else in my house, heh.

It worked

I stript my screws on the next one i was cleaning though D:<

It's a rotary tool. A wire brush should do the job pretty well.

Get cotton wool tips (the kind people clean their ears with), get some white vinegar, dip the tips in the vinegar, scrub the corrosion. It melts off like nothing

A cleaning product called CLR will dissolve all corrosion in 10 minutes.  Just soak in a glass cup.

thats like a mini sander right?

I'm not really pro at soldering so I'm hoping for the most simplest method