Using the tool is straightforward, but you will need to have a way to run homebrew applications on your 3DS. Note: You typically cannot use this if the Homebrew Launcher itself won't open, unless you have another entry point (like a secondary exploit app installed on your home menu).
: For hardware issues on a real 3DS, you may need to delete the specific extdata folder matching your region (USA: 000002cd , EUR: 000002ce , JPN: 000002cc ) from the SD card. errfix3dsx