This might be what you’re looking for.
https://www.sparkfun.com/products/10063
You’ll have to find a wiring diagram, because, unfortunately, this hasn’t really been done.
I’ve seen and read plenty of threads about the standard GBA backlit mod not being bright enough, but my problem is the opposite. I was wondering if there was another solder point that would allow for less brightness? Maybe trick the volume wheele into dimming the display instead of adjusting the...