Blue Screen of Death caused by Gateway 3DS card, resulting in a brick
krisztian1997 and bkifft have written some code available on Github which can be run on a Raspberry Pi or an Arduino (models without a 3.3v output will need either a voltage divider or an SD card shield) to unbrick a 3DS.
It requires a hardware mod, (opening up the 3DS and soldering some pins to the eMMC) but never the less, it is now possible without having to send in your 3DS to the Gateway team!
You must have a NAND backup (created previously from emuNAND) in order to restore the firmware after the eMMC has been unlocked and erased.
eMMC Pinout (dat3 only needed if using Arduino): http://gbatemp.net/attachments/vrije-opmerking_20140126_123816_01-jpg.6106/
Code (Arduino): https://github.com/krisztian1997/3dsunbricker
Code (Raspberry Pi): https://github.com/bkifft/RPU