hello, /vr/. /g/ sent me here because of this issue:
my childhood pokemon silver cartridge just doesn't work anymore, even after a battery replacement. Trying to troubleshoot online seems very difficult on a surface level since almost every solution I see is "just replace the battery lol" "clean contacts lol" which i've already done. guy at a repair shop looked it over and said it might be some kind of ram issue, but he didn't want to do any real troubleshooting or repair on it. does anyone here have any advice on where to start? if it's not too crazy difficult i'm looking to turn this into a side project so i can learn more about soldering and repairing these old game cartridges. Can't take a picture of the board right now since I lost the screwdriver, have another one coming this week. I'm only entertaining repair as an option here because I saw this video a few years back and it gives me some kind of hope:
https://www.youtube.com/watch?v=xKR1NIwxSdo

No.
Every field.
L2read4faggot

>>11850782 (OP)
Just buy another cart

The first step would be reflowing the ROM chip, which is the IC on the bottom right of the PCB. If no luck, reflow the MBC3 chip, the small IC on the left with the pins coming out of all four sides.

>>11850782 (OP)
I'm guessing that it boots up and plays normally, but if you shut off the Gameboy the save file is gone?
One thing to test: Start a game and save. Now push A+B+Start+Select. This does a soft reset -- you're rebooting the game without removing power from the RAM chip. You'll see one of 2 outcomes:
1. Your save is there and loads normally. The RAM chip works fine but loses data when the power goes out. Either you fucked up installing the new battery, installed a dead battery, or something is wrong with another component between where the battery power goes in and where it powers the RAM chip.
2. Your save is gone, or is there but it says it's corrupted. Fault inside the RAM chip or one of the RAM chip pins isn't soldered well. Or one of the contacts that go to it is still dirty -- I've had contact issues even after a thorough scrubbing sometimes.
Another test: If you have another Gameboy, GB Player, Super Gameboy, or N64 Transfer Pak + Pokemon Stadium 2 (I think; unsure if the emulator caches the save file in system RAM though), do the same test as above on that. If it behaves differently, the cartridge connector inside your Gameboy is dirty. You can also try another cartridge that has saving in the same Gemeboy.
Cleaning GB slot contacts: I've had the best luck with a piece of corrugated box cardboard. Cut it to the width of the edge connector on the PCB inside the cartridge. Wet the end with IPA rubbing alcohol. Push it in and out of the cartridge slot repeatedly to scrub the pins. Always in and out, never back and forth or you might bend a pin.
Cleaning a GB cartridge connector: Dip a q-tip in IPA, press out excess so you don't dribble it all over inside the cartridge. Stick it into the end (it's a tight fit) with the connector facing down so any drips go out not in. Scrub back and forth over and over. For stubborn cartridges, open the shell and use a pink pencil eraser like picrel to erase the dirt off the pins.

>>11850825
To add, I'm not sure if the problem is as prevalent on original and GBC enhanced carts like Gen 2 Pokemon games, but dedicated GBC games are known for having cracked solder joints preventing them from booting, and you can find some YouTube videos where people revive a bunch simply by reflowing solder joints.
The go-to method involves drag soldering, but if you aren't comfortable with soldering, I wouldn't suggest experimenting with this method on a cart that you care about (you can sometimes wind up with solder bridges, and while there are methods to clear them, they aren't foolproof and you might wind up tearing yiur hair out trying to clear a bridge), and perhaps instead just carefully reflowing a pin at a time, iron perpendicular to the chip. In either case, you will want to inspect for solder bridges, preferably with the aid of a multimeter, making especially sure that the any voltage pins aren't bridged to anywhere they shouldn't be.