Hello! I came here in hopes of fixing my bricked DS flashcard!
I've done this in the past when I CFW'd my own o3DS XL, where I flashed my R4i SDHC RTS Lite and used it to do the whole CFW installation shabam, and naturally once I was done I simply restored it on the ntrboot screen (holding start during powerup). It all worked back then. Now it's been a while and I've definitely got a little rusty on the knowledge of 3DS CFW, a friend of mine wants me to hack his doorstop 2DS.
After running ntrflash or whatever it's called, the 2DS should boot some magical screen after holding X+Start+Select+Power for several seconds when in sleep mode (As seen in the 3ds.guide). Unfortunately that's not what happened; see I either made a mistake of not placing the correct files on the 2DS SD card, or I misplaced files on the R4i SDHC. All resulting in a 2DS that appears to still be in stock retail (no cfw installed) and a non-functional R4i SDHC that isn't detected when placed in any of my DS devices.
My first thoughts were; "Huh, weird. I guess I'll restore the flash of my R4i SDHC and try again." I placed the Flashcart in my trusty o3DS XL and booted up the ntrflash manager thingie. At first restoring didn't work; giving me a "Restore file is missing" or something like that. Then from my empty skull I thought it would be a good idea to 'Dump Flash'. After I did that the 'Restore Flashcard' it seemed like it worked, considering that I got a message saying that the restoration was successful.
That's where things go down hill, after rebooting the o3DS XL, the flashcard didn't show up. I've tried to restore it a couple times now. It's getting me no where. I heard that there is a backup file or something on 3ds.guide that will help me, but I haven't looked too deep into it. At first I didn't want to include the whole story but I believe that it was necessary.
Thanks!