All the original japanese pokemon games, and final fantasy legends 2+3. Also I found the issue. the guide I followed for installing the backlight was wrong. I was tinkering around and found out the backlight's negetive wire was in the wrong soder. Thanks for the help though!

So about a month ago I modded a dmg gameboy with a backlight and new case. I havent had any games for it cause I sold all of mine years ago, but  I finnaly got some. when testing the gameboy it always showed the shadded nintendo bar like normal, but when I put a game it it would show a blank screen with a black line across the top like it was trying to show the nintendo logo.
My question is why isnt it working?