After many attempts I have finally gotten my downgraded n3DS XL to boot EmuNAND properly. I first tried the Catch-All tutorial which would not install FBI due to an unknown error. After that I tried the RxTools Google Doc which would not boot to EmuNAND at all and only displayed a black screen...
Every tutorial I tried on my n3DS XL failed (boot emunand to black top screen and red bottom screen) until I reformatted my sd card and followed this: https://gbatemp.net/threads/tutorial-setting-up-9-0-9-2-n3ds-xl-for-rxtools-cfw-including-emunand-coldboot-cia-manager.405589/ which worked first...
Since nobody has replied to you yet, I have checked my copy and it does not appear to load anything from the SD card on startup (no blue squares or text indicating any access to the SD card).