I wanted follow up on this old post about the Game Boy Micro: Game Boy/Color/Advance OT + Collecting Thread - Get into it! - #67 by harborline_765
Basically, the START and SELECT buttons differ on the European models, but I couldn’t take photos because I had lent my EUR model to a friend. I’ve got it back now so here’s some images about this, which I don’t think has been documented anywhere:
JPN model before European model:
While they both produce a bright blue or red light, it’s clear the original Japanese/North American models use what are probably more expensive parts. The words are etched into the chrome buttons there, producing very neat highlighted and lit letters, whereas it’s pretty washed out on the faux-chrome European buttons.
I wonder why they switched the buttons? Only thing I can think of is maybe they used mercury to make the original buttons - whose presence in the WarioWare Twisted cartridge caused that game to be cancelled in the EU due to regulation (I forget which one)