What ChaosX1022 says is correct. You don't have a bad/fake SD card. Sky3DS writes the game to the card in RAW format (that's what the format option does to the SD card) and doesn't allow fragmented files like a traditional file system (FAT/NTFS). Files are written sequentially and contiguously...
I've got pretty much the same results as you. Only thing that seems to work is the default N3DS card.
Toshiba 4GB Class 4 (default New 3DS memory card): Work
Sandisk 8GB Class 2: Black/White screens after pressing A button
Generic eBay 8GB: Black/White screens after pressing A button
I feel like school, back when I was actually in school, was more entertaining though, because of how much I get to interact with people, hang out with friends, and other stuff like that. All I get to talk to at work is my boring coworkers lol