look for the solderjoints underneath the screen. in most cases when removing the refclecting layer from behind the screen, it gets loose on min. 2 Pins. I had the same issue and just resoldered 2 pins.

The ribbon cables are very robust. I'm sure it's shorting out, try and cover up where you soldered the backlight wires to. could you maybe provide me a picture of the internals?

I've been having this same problem today. I was having D-pad issues, fixed that but my positive backlight lead came unsoldered in the process, fixed that, and now i just have a blank screen. I'm pretty sure I've stressed the ribbon cable too much as well from having to keep disassembling and testing.

You might have stressed the ribbon cable too much. Maybe you could try the vertical lines reflow trick and see if that works?

but everything else like I said before the sound, the backlight still works properly

When I pressed the ribbon cable underneath the LCD the screen started to show the loaded up game that was inserted (which was Tetris) stayed on the screen for about 3 seconds til it went blank again so I pressed on the ribbon cable but the screen didnt show like it did previously just stayed blank

It's still worth checking again, there might be something obviously disconnected…

I think the ribbon cable underneath the LCD lost connection or something...  best to look for another dmg now

Nope

…Do you have the contrast turned all the way down?

Also I still hear the sounds when it turns on

yeah I connected it

Did you remember to reconnect the ribbon cable that joins the front and back PCB? Was that cable damaged in some way?

Backlight works but when I turn it on nothing spears on the screen /: no Nintendo bar ... Does anyone know the reason for this??