Sadly I am a Mac user so the only program that I found was available for Mac was Step 1 the SD Card Memory Formatter, and then I formatted it again with the Mac Disk Utility. It wasn't originally in a FAT32 format. I currently don't have a spare SD card so I added the boot.firm file to my same...
A few years ago I downloaded CFW for my 3DS in hopes of being able to play a Pokemon game and bypass the region lock. I don't exactly remember what I downloaded, but I know that on my SD card I have Luma, GM9. ect...
Fast forward to now, I start playing my 3DS again which works completely fine...