It can be NAND corruption. If it is, your 3ds is fucked.
But before you do anything, try to clean your 3ds' sd reader.
A9LH works, sd doesn't. And you've checked the card. That means your sd reader could be dirty, defect or whatsoever.
But before you do anything, try to clean your 3ds' sd reader.
A9LH works, sd doesn't. And you've checked the card. That means your sd reader could be dirty, defect or whatsoever.