Add ntrboot setup guide + ntrboot files (#104)

* ntrboot guide

* minor editing

* Typo + change bullets to follow CONTRIBUTING.md

---------

Co-authored-by: Rolfie <[email protected]>

pages/_en-US/ds-index/hardmod.md

@@ -10,6 +10,9 @@ tabs:
     other: macOS/Linux
 ---
 
+Hardmodding can easily damage your DSi. If you're trying to unbrick your DSi, then you should try [ntrboot](ntrboot) first.
+{:.alert .alert-danger}
+
 Hardmodding is when you physically solder the motherboard of the Nintendo DSi to an SD card adapter in order to be read on a computer. This is useful for restoring NAND backups, viewing NAND on your PC, etc...
 
 ### Nintendo DS

pages/_en-US/ds-index/ntrboot.md

@@ -0,0 +1,64 @@
+---
+lang: en-US
+layout: wiki
+section: ds-index
+category: guides
+title: ntrboot
+description: How to use ntrboot on a Nintendo DSi
+tabs:
+  - dsi: DS/DSi
+    3ds: 3DS
+---
+
+**ntrboot** is a recovery mode built into every DSi and 3DS. If a specially signed cartridge is inserted and a button combo is held, the cartridge will be loaded before anything on NAND. Nintendo used this to set up blank units in the factory, but it can be used as a recovery mode if the NAND is corrupted, missing, or otherwise damaged. 
+
+### Required hardware
+
+To use ntrboot on your DSi you will need:
+   - An ntrboot compatible flashcard. [Here's a list of working carts](https://www.flashcarts.net/ntrboot-ds-carts.html?tab=flashable). Ignore the pre-flashed ones as those use the 3DS version of ntrboot.
+   - A magnet to trigger ntrboot
+   - A second DSi/3DS in order to flash ntrboot to the flashcard
+
+{% capture tab-dsi %}
+
+You must have already followed [dsi.cfw.guide](https://dsi.cfw.guide) and have a way of running homebrew.
+{:.alert .alert-warning}
+
+1. Download the [ntrboot image](/assets/files/default.gcd) to your DSi SD card as `sdmc:/ntrboot/default.gcd`
+1. Download the [ntrboot flasher](/assets/files/ntrboot_flasher_nds.nds) to anywhere on your SD card
+1. Insert your SD card into a modded DSi, then run the ntrboot flasher
+1. Follow the instructions on screen. Select your cartridge from the list, back up your flashcard, then inject ntrboot. You must select the "TWL" option
+
+{% endcapture tab-dsi %}
+{% assign tab-dsi = tab-dsi | split: "////////" %}
+
+
+{% capture tab-3ds %}
+
+You must have already followed [3ds.hacks.guide](https://3ds.hacks.guide) and have luma installed.
+{:.alert .alert-warning}
+
+1. Download the [ntrboot image](/assets/files/default.gcd) to your 3DS SD card as `sdmc:/ntrboot/default.gcd`
+1. Download the [ntrboot flasher](/assets/files/ntrboot_flasher.firm) to your SD card as `sdmc:/luma/payloads/ntrboot_flasher.firm`
+1. Insert your SD card into a modded 3DS. Hold `START` to open the luma chainloader, then select the ntrboot flasher
+1. Follow the instructions on screen. Select your cartridge from the list, back up your flashcard, then inject ntrboot. You must select the "TWL" option
+
+{% endcapture tab-3ds %}
+{% assign tab-3ds = tab-3ds | split: "////////" %}
+
+### Flashing ntrboot
+{% assign tabs = tab-dsi | concat: tab-3ds %}
+{% include tabs.html index=0 tabs=tabs %}
+
+### Running ntrboot
+
+1. Download any homebrew to the SD card as `sdmc:/ntrboot.nds`. For this example we'll use [GodMode9i](https://github.com/DS-Homebrew/GodMode9i/releases/).
+1. Insert your SD card and the ntrboot flashcard in your DSi
+1. Place a magnet near the `ABXY` buttons until you trigger sleep mode
+1. Turn off your DSi
+1. With the magnet in place, hold `start` + `select` + `x` and turn the DSi on
+1. GodMode9i should now boot
+
+If ntrboot does nothing and you're sure that the magnet and button combo are correct, ntrboot might not be working. Try following the flashing instructions again with [this ntrboot image](/assets/files/default_green.gcd) and see if ntrboot loads a green screen. If it does not, your flashcard may be incompatible and you will need to ask in the [DS(i) Mode Hacking](https://ds-homebrew.com/discord) Discord server.
+
+If you get a "NAND Init failure" error or don't see the NAND from ntrboot, you will need to boot the homebrew you want through another program (eg. launching SafeNANDManager through GodMode9i). There is an issue with ntrboot in which the CID/ConsoleID are not properly set up on boot, so mounting the NAND for editing/recovery will not work right away.