Here's how to bypass the ribbon connector from the GBA, which from my experience doesn't work well - took me hours to work it out!
Note, this is for the 40 pin GBA (by the ribbon cable it says "40" or "32" - 32 is the same but the contacts on the board look slightly different but still the same):



Result looks crisp on a screen.
He's a pinout I got elsewhere years ago for RGB:
