EDIT: This tutorial maybe outdated, technically it still work but please use Plailect's Guide, it covers even more things:
https://plailect.github.io/Guide/
EDIT: MANY USERS ALREADY BRICKED THEIR DEVICE, SO BE ABSOLUTELY SURE WHAT TO DO, THIS IS VERY DANGEROUS. WITHOUT A HARDMOD AND A NAND BACKUP A BRICK IS PERMANENT!!!
I'm doing this tutorial quickly...
[Tutorial] Downgrade 3DS with sysUpdater
https://plailect.github.io/Guide/
EDIT: MANY USERS ALREADY BRICKED THEIR DEVICE, SO BE ABSOLUTELY SURE WHAT TO DO, THIS IS VERY DANGEROUS. WITHOUT A HARDMOD AND A NAND BACKUP A BRICK IS PERMANENT!!!
I'm doing this tutorial quickly...
[Tutorial] Downgrade 3DS with sysUpdater