It was modded to get a black and gold theme with two different shells, before a Zelda decal was then added on the top face. Mint refers to the outer condition in respect to a new GBA SP, since modded items can't be otherwise compared. I'm not sure exactly why it doesn't play or connect to GB/GBC games yet does perfectly well with GBA. Though it is able to detect them.
And I've heard of regular frontlit GBA SP's being modded with backlit components. Though this is definitely a genuine AGS-101.