The CIA files...
Took about 50 tries for my damn N3DS to recognize them, but I'm finally down to 9.2 from 10.3. Not an easy downgrade at all for me. Don't know if it helped, but here's the last thing I tried before it worked:
1. Backup EVERYTHING on the SD card you don't want, wipe it.
2. Put a fresh starter pack, sysUpdate, and the CIA files onto the card.
3. Use your favorite entry point. I usually boot using BrowserHax or MenuHax... IronHax and Oot3DHax tend to soft brick my N3DS 50% of the time, while BrowserHax and MenuHax are pretty solid. Do whatever is convenient, really.
4. Run FTPBrony, wait about ten seconds, then back out with B. RUNNING sysUpdate DIRECTLY SOFT-BRICKED MY N3DS
EVERY SINGLE TIME!!!
5. Run sysUpdate, press Y, and pray.
if sysUpdate crashes to a blackscreen upon startup, its safe to reset. return to step 3.
if sysUpdate freezes upon pressing Y, its safe to reset. return to step 3.
if sysUpdate crashes after pressing Y with an error message like "CIA files could not be read!" its safe to reset. return to step 3.
if it says something like "Reading CIA files..." you are one lucky dog.
FOR THOSE LOOKING FOR THE CIA FILES:
linking them is a no-no, but i'll tell you how i found them.
1. i watched the video on this site
http://wololo.net/2016/01/04/3ds-system-software-downgrade-tutorial/
2. i pause the video at about 3:33.
3. i maximized the video and changed the resolution to 1080.
3. i copied down a long and ugly link.
Home this is of some help. Don't give up. It works.