Got "Broken" SNES Mini from eBay. Won't read special chip games.

So I got a SNES Mini and tested it with two copies of Chrono Trigger (1 JP and 1 self made US repro), which both work perfectly. Whenever I try Yoshi's Island (JP), I get either a black screen or corrupted graphics, but the game never starts. With my SD2SNES, the menu loads fine, but the RTC is completely messed up and the list of games are just random text. I tried the SD2SNES diagnostics tool, but it never got past the yellow screen (I waited 30 minutes). I attached the log file anyway. Options in the SD2SNES such as System Information just crashes the whole system.

Another issue I had (which I already fixed) was that the reset capacitor was bad (when I powered on, I had to reset for the game to actually load), so I just recapped the whole console. This fixed the reset issue, but did nothing to fix special chip games. Since my SD2SNES doesn't work, I cannot run any diagnostics ROM. Both the SD2SNES and Yoshi's Island are clean and work perfectly in my other SNES and my SFC (both SHVC-CPU-01).

I also RGB modded my Mini, but that did not impact anything since I tested before with the same results.

The first thing that I did when I got it was clean the cartridge slot as best as possible, although it is still a bit rusty. I would remove it and soak it in vinegar, but it is not detachable like the early SNESs were. Desoldering it would be extremely tedious.

 

Test the extra pins that special chip games use for continuity on the console. The rust may have destroyed the traces. If you do not understand what I mean by extra pins, then compare the teeth or rather fingers of your special chip games to a normal game and you will notice that special chip games have more fingers. Fingers being the technical term for contacts.

 

Do you know where I can find the SNES Mini schematics to I can find where those traces lead to? The brown color of the bottom makes it hard to see. Also, I'm not too sure if Yoshi's Island uses those extra pins. I remember trying to block them off with electrical tape to see what happened and the game still worked just fine.

EDIT: So one of the pins came clean off while I was cleaning it, so there was clearly something wrong with the connector. Now no games are starting. Is there any place that I can get a replacement 62 pin connector for a decent price?

EDIT2: It was one of the VCC pins. Luckily, there's another one available, so carts still read. Now there is a buzzing sound while loading the game and a constant hum while the game is running. It's like I can hear the games load.

EDIT3: So Yoshi's Island works now. Now I just need to figure out the buzzing. Does anyone know which pins SPC data is loaded from?

 

The buzzing might just be the cart direct audio pins. They're on the outside as well (just like the special cart pins).
http://www.caitsith2.net/snes/flashcart/cart-chip-pinouts.html

 

Well now it's just not reading anything, just like there is no cartridge even inserted. Sync signal is not changing, but it is trying to change. Still getting 5v, though.

EDIT: It still reads sometimes. I'm going to desolder it and give it a serious cleaning. Buzzing is gone now.

EDIT2: Didn't desolder it, but reflowed all of the points. Games are now working first time every try, so success... I guess?

EDIT3: Randomly died during Yoshi's Island gameplay. Now it's doing the same thing as before where it won't read any game. I have no idea what's going on.