With the way arm9loaderhax works right now, a formatted, dead, or otherwise deleted SD/microSD prevents you from booting the 3DS at all. Does that mean you have a brick? Not in the least! It is quite possible, even easy, to recover the ability to boot your 3DS, as long as you have a functioning SD/microSD. The purpose of this guide is to help you get your 3DS back into working order after you've lost the data on the system's SD/microSD (hereafter referred to as "SD card" or "SD"). It assumes...
[Tutorial] A9LH Users: Recover From Formatted/Deleted SD Card
[Tutorial] A9LH Users: Recover From Formatted/Deleted SD Card