Add SD card flashing instructions

Author: raccube

images/content/kit/etcher.png

@@ -9,3 +9,26 @@ Brain Board
 <img src="{{ site.baseurl }}/images/content/kit/brain.png" alt="A photo of a brain board" title="A brain board" class="right" />
 The Odroid U3+ Brain Board provided with your kit is what runs the code you write
 and controls the other peripheral boards.
+
+It can be controlled remotely over [WiFi](/docs/kit/wifi).
+
+### Flashing SD card
+
+To fully update your Brain Board's software, or refresh it if you think it's not working correctly, you can flash our SD card image onto the microSD card in your Brain Board.
+
+To update the SD card, you'll need to download our image, `robot-image.img.xz`. The flashing procedure is identical to flashing Raspberry Pi images.
+
+## Etcher
+We recommend using [etcher](https://etcher.io), as it's simple to use, and available on Windows, macOS and Linux. If you're familiar with Raspberry Pis or other similar boards and have flashed images before with a different tool, that will also work.
+
+![Etcher example]({{ site.baseurl }}/images/content/kit/etcher.png)
+
+<div class="info">
+If you choose to use a tool other than Etcher, you may need to extract the `robot-image.img.xz` to `robot-image.img`. There are many tools available for this, e.g. [7-zip](http://www.7-zip.org/).
+</div>
+
+### Flashing
+
+1. Open Etcher and select the `robot-image.img.xz` file you downloaded
+2. Select your SD card from the devices window
+3. Click 'Flash!'