Requirements:

Homebrewed Switch

Physical or Digital copy of BOTW for Switch

Hey, everyone! This guide will show you how to install the Second Wind mod onto your Switch. For simplicity, I'm going to assume you already have a homebrewed Switch. If you don't, I recommend this tutorial or this tutorial.

Firstly, the BNP file on the Second Wind GitHub can't just be used as-is or extracted onto the SD card and loaded. For copyright and filesize reasons, the mod has been stripped of as many game assets as possible, so trying to use it this way will just crash the game, because the mod contains only the modified files. To create a full copy of the mod that can be loaded into the game, you need to use BCML.

The first step to using BCML for Switch is to dump the romFS of the game, which is a fancy way of saying "all of the game's decrypted files". Since the mod only includes edited files, BCML needs a copy of the regular game to create a usable copy.

Download the latest Lockpick_RCM.bin from GitHub. Either place it on your SD card at bootloader\payloads then select it in Hekate's payloads menu, or inject it with a tool like TegraRcmGUI (like you would the Hekate payload). Press POWER to select the Dump from SysNAND option. Reboot to Hekate, or reboot to RCM and inject Hekate.

Download NXDumpTool and place the NRO file in the switch\ folder on your SD card. Boot the Switch back into CFW, then Boot Breath of the Wild and hold R after you select your profile. This should load the homebrew menu. Select NXDumpTool in the list, and hit A to launch it.

Put in the cartridge, then select Dump gamecard content in NXDumpTool and go down to RomFS options. Go down to Use update/DLC, and select the 01007EF00011E800 v786432 (0.0.12.0) (UPD) option. Leave the other two options set to No, then press RomFS section data dump. This takes about an hour on my system, but your speed may vary based on how fast your micro SD card's is.

Go back to the main menu of NXDumpTool and select Dump installed SD card / eMMC content. Because it's a physical copy (the base game isn't on the SD card or console storage), the DLC is considered an "orphan" title. To show these, press Y. The update has already been dumped, so you just need to dump the DLCs. There are 2 DLCs listed, one ending in F001 and one ending in F002. Dump bth, the same way as the Base game/update (RomFS options > RomFS section data dump). The first DLC should take about 5 minutes to dump, and the second one will be instant, since it only has 1 text file.

Select Dump installed SD card / eMMC content in NXDumpTool, then select BotW. Go into RomFS options, then go down to Use update/DLC and select The Legend of Zelda: Breath of the Wild v786432 (01007EF00011E800) (Update). Press RomFS section data dump, and wait about an hour for all the files to be dumped. When it finishes, repeat the same process, but selecting the first DLC (01007EF00011F001). Ignore the other listed "DLC", it doesn't actually have any content in it.

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Run this script (by Shadów#1337 on discord). Once installed, you can run BCML with the shortcut generated by the script, or by running bcml in a command prompt. (NOT the python console)

If for whatever reason the script doesn't work for you, click this dropdown to see manual installation instructions.

Manual BCML Install

BCML requires Python 3.8.10 or 3.7.9, and the x64 Visual C++ redistributable. When you open the Python installer, there will be a Add Python to PATH checkbox. You MUST check this box, or else BCML can't be installed.

Now install the x64 Visual C++ redistributable (no special steps are needed).

Open a command prompt anywhere (if you don't know how, just type cmd into Windows Search). Run pip install bcml (in the normal cmd prompt, NOT the python console). If you run it in the python console, it will give you a syntax error. If it says that pip is not a recognized command, this usually means you didn't add Python to PATH, so go back and re-install it. You should see a bunch of progress bars, and then a success message. If it throws lots of errors, make sure you don't have Python 3.9. Now run pip install cefpython3, and run bcml to start BCML.

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Copy both folders at sd:\switch\nxdumptool\RomFS to somewhere on your PC. Make sure you don't put them in a OneDrive folder, or else BCML won't be able to read them. Now open BCML, and proceed until it asks you for filepaths. Enable the Use Switch mode and Disable hard links for master mod (IMPORTANT: if you don't check this box, BCML will delete your contents folder and everything inside it) boxes, then set the Merged Export Directory to sd:\atmosphere\contents, so that BCML will automatically send your mods to the SD card. Set the Base+Update Directory to wherever you copied the The Legend of Zelda_ Breath of the Wild v786432 (01007EF00011E800) (UPD) folder, and the DLC to wherever you copied the DLC folder. Select a language, then hit save. If every box has a checkmark and it won't let you save your settings, copy down all the filepaths in Notepad, reboot BCML, and input them again. For reference, this is my settings screen:

Download the BNP file from the Second Wind GitHub. Press the + button in the bottom right of BCML, hit Browse, and select the BNP file. Make sure your SD card is connected, then install them. BCML should automatically install it to your Switch. Boot into Atmosphere, and start playing the mod!