Bad luck man. You've killed the display. Perhaps too much pressure on the ribbon beneath the LCD.
Does it always stay like that? fiddle around with it.
If you are new to this things, try to use a broken gameboy for training before doing it on your oficial ones.
yeah when I move it around, the display will go back to normal, but it always eventually looks like the pictures above. What would be the cause of those lines? I understand that the ribbon is sensitive, but the ribbon looks fine.
This here isn't a case of vertical lines, it's a physical rip somewhere in the ribbon cable. The one under the LCD I'm sure. Check the solder connections on the cable under the LCD, and you'll probably see a broken connection.
Check for breaks in the flat flex cable that goes up from the board to the LCD, for example around the metal clip that holds in it plac. Do the same with the stuff under the PCB. Go through each of those solder points (PCB<->flat flex) with a soldering iron really quickly. Just a quick dab on each joint so it melts and then cools. Make sure the cable is held in place during the procedure and doesn't come off while the solder is melt.
It's a shame you broke one of those left-handed DMGs... those things are ultra rare!
Also try a different cartridge