Firstly , let’s figure out something , why we need to backup the 3DS console NAND system file ?
I believe you heard about “brickers” issue before , backup 3ds/3ds xl or 2ds console can avoid this issue .In case your console get brick , just copy the backup of the nintendo system file into the sd card , then your console will be brought back to life . Here is the step by step about how to backup the 3DS console NAND system file when use gateway 3ds .
Make sure your gateway 3ds is this one : Gateway 3ds flashcart
Before starting , these things required:
Step 1 Download the latest gateway 3ds firmware: gateway 3ds V2.1 OMEGA
After donwload , you would get :
You can see the files of the folder , then we will use them separately
Step 2 set up the gateway 3ds blue card
（a）Get a micro sd card , any size would be fine (format it before you use it ) . Open the blue card folder, and copy all the contents inside to the root of your micro sd card. Then the contents on the root of the micro sd card should be like this as below .
（b）insert the gateway 3ds blue card with sd card together into your 3ds console. power on
（c）Click the icon to enter
（d）Click the gateway installer to install
（e） Click A to start according to its Hint
（f） Just wait until the installation finish
（g） Click the “ Home” button back to the home menu and keep the power on.
（h） Then take out the gateway 3ds blue card.
Step 3 Set up the sd card.
(a) Format the sd card before you use it
(b) Back to the folder which you have downloaded in the step 1, find the GW-OMGEGA-2.1-RELEASE ， as the pic below
(c) open it and you can see the Launcher.dat file
(d) Copy it and put it on the root of your sd card.
(e) Insert the sd card back into the 3ds slot, go to the system settings nintendo.
(f) Click it
(g) Click other settings
(h) Click Profile
(i) then the console will go the gateway menu
Use the Left/right button and move to the third icon which is the “Backup system NAND” icon
Just press “Start” to backup NAND, then it will start working, it needs about 10 mins for the backup, just wait until it finishes.
Done the backup successfully , take out the SD card and copy all the files and save them on your PC(use it just in case the nintendo get bricked ).