For support (in English or German) with GodMode9, as well as help with scripting and to get updates and info, join GodMode9 on Discord.
GodMode9 is a full access file browser for the Nintendo 3DS console, giving you access to your SD card, the FAT partitions inside your SysNAND and EmuNAND, and basically anything else. Among other functionality, you can copy, delete, rename files, and create folders.
Note that if you have any payload files other than GodMode9.firm in the /luma/payloads/ folder on your SD card, holding Start on boot will display a "chainloader menu" where you will have to use the D-Pad and the A button to select "GodMode9" for these instructions.
GodMode9 is powerful software that has the capability to modify essentially anything on your console. Though many of these modifications are locked behind a permissions system, and it is impossible to accidentally perform dangerous actions without deliberately unlocking permissions, you should still follow instructions carefully and keep backups just in case.
Updating GodMode9
Some of the instructions below are only applicable to the latest version of GodMode9, and as such you should follow this section to update your copy before continuing. Overwrite any existing files.
What You Need
The latest release of GodMode9 (the GodMode9 .zip file)
Instructions
Power off your console
Insert your SD card into your computer
Open the luma folder on your SD card and create a folder named payloads inside, if it does not already exist
Copy GodMode9.firm from the GodMode9 .zip to the payloads folder
Copy the gm9 folder from the GodMode9 .zip to the root of your SD card
Press and hold Start, and while holding Start, power on your console. This will launch GodMode9
Press Home to bring up the action menu
Select "Scripts..."
Select "GM9Megascript"
Select "Backup Options"
Select "SysNAND Backup"
Press A to confirm
This process will take some time
If you get an error, make sure that you have at least 1.3GB of free space on your SD card
Press A to continue
Press B to return to the main menu
Select "Exit"
Press A to relock write permissions if prompted
Navigate to [S:] SYSNAND VIRTUAL
Press A on essential.exefs to select it
Select "Copy to 0:/gm9/out"
If you see "Destination already exists", press A on "Overwrite file(s)"
Press A to continue
Press and hold R, and while holding R, press START to power off your console
Insert your SD card into your computer
Copy <date>_<serialnumber>_sysnand_##.bin, <date>_<serialnumber>_sysnand_##.bin.sha, and essential.exefs from the /gm9/out/ folder on your SD card to a safe location on your computer
Copy these backups to multiple locations (such as online file storage, an external hard drive, etc.)
These backups will save you from a brick and/or help you recover files from the NAND image if anything goes wrong in the future
Delete <date>_<serialnumber>_sysnand_##.bin and <date>_<serialnumber>_sysnand_##.bin.sha from the /gm9/out/ folder on your SD card after copying it
The other backup files are negligible in size and may be kept on your SD card for ease of access
Your NAND backup has been successfully restored. You can now delete <date>_<serialnumber>_sysnand_##.bin from your SD card.
Injecting any .CIA app into Health & Safety
Note that you cannot inject something that is larger than Health & Safety. You'll only be able to install inject relatively small homebrew (no retail games).
Press and hold Start, and while holding Start, power on your console. This will launch GodMode9
Navigate to the location of your .cia file
Press A on the .cia file to select it
Select "CIA image options..."
Select "Mount image to drive"
Press A on the .app file
Select "NCCH image options
Select "Inject to H&S"
Press A to unlock SysNAND (lvl1) writing, then input the key combo given
Your SD card has successfully been formatted for use with the 3DS.
Removing an NNID without formatting your console
This will only remove the NNID from the console locally. It will not unlink it on Nintendo's servers. To use it on a different console, you must perform a System Transfer, or contact Nintendo Support.