Game Boy Color China AGS-101 Adapter
In order to install a backlight AGS-101 screen in a game boy color, you'll need a method to adapt the Nintendo Game Boy PCB (electronics) to a screen that is not intended to connect to it. (AGS-101). One of these options is to use a small PCB created in China. The AGS-101 flex cable plugs into it, and a supplied ribbon cable connect the China PCB to the Game Boy Color.
Now, the only wrinkle is that there is a built in brightness controller. You need to solder three (or two as I'll show) wires. Otherwise, the screen will cycle from low brightness to it's highest setting. If you wire the three wires according to the China adapter directions, it will work just fine. However, personally I find it a pain to find space for the wires when assembling.
Instead, what I do is just wire two wires. And those two wires are routed to two different locations. This limits the brightness settings to low and high. I think it's worth it to aide in assembly.
Below image is the overall wiring. There are 3 solder pads on the China PCB. 1 and 3 will be used. 2 will not.