chromebook-guide/_pages/en_US/halcyon.txt

---
title: "E-Halcyon"
---

{% include toc title="Table of Contents" %}

## Prerequisites

- A USB drive, 8gb or larger
- A Linux system to build E-Halcyon

## Section I - Getting a RecoMod Image

First, you'll need to head to [chrome100](https://chrome100.dev/) and find a v107 recovery image for your board. Once you have it, you need to download it on your Linux system (probably with `wget` or `curl`) and run the following commands, replacing `/path/to/recovery/image.bin` with the exact path to your (unzipped) recovery image:

```sh
git clone https://github.com/MercuryWorkshop/RecoMod
cd RecoMod
chmod +x recomod.sh
sudo ./recomod.sh -i /path/to/recovery/image.bin --halcyon --rw_legacy
```

After a few minutes, the script should output a success message and you'll be good to continue.

## Section II - Flashing your Image and Booting

By this point, you should have the steps down. Just flash the image that you just modified identically to how you flashed SH1mmer previously. From here, the steps differ significantly.

Enter recovery mode (`Esc+Refresh+Power`) and enable developer mode (`Ctrl+D` and `Enter`). At the "developer mode blocked" screen, enter recovery mode again (`Esc+Refresh+Power`). At this point, you should plug in your RecoMod drive and begin to spam the `E` key on the keyboard. This is a critical step and cannot be skipped. RecoMod will begin a 5-minute wait sequence (you can watch it tick down if you like, it's in the top left hand corner of the screen), at which point you can stop spamming the `E` key. Once the timer nears the end, begin spamming the `E` key again. After a few seconds, a boot screen will show and you will be presented with a menu.

## Section III - Booting or Installing E-Halcyon

Select `activate halcyon environment` in the menu with the arrow keys and press `Enter`. You have a few choices from here:

+ Install semi-tethered E-Halcyon
  + Still requires a USB drive to boot, but allows the drive to be disconnected after initial bootstrapping
+ Boot E-Halcyon straight from the drive
  + Requires the drive to be plugged in at all times or the system will crash
  
If you want to install E-Halcyon, navigate to `Install halcyon semi-tethered` and press enter. Wait for it to finish (it can take up to 5 minutes) and then select `activate halcyon environment` and `Boot halcyon semi-tethered`. Your system should reboot and you will be booted into a fully unenrolled environment.

Otherwise, select `Boot halcyon tethered` and your system will reboot into a one-time fully unenrolled environment that you can use as much as you want, as long as you don't unplug your USB drive.

## Section IV - Semi-Tethered Restrictions

If you didn't install E-Halcyon in semi-tethered mode, this section doesn't apply to you. You can skip it and get on with your day.

Semi-tethered halcyon comes with some restrictions:
+ Booting ChromeOS normall will result in a "ChromeOS is missing or damaged" screen
+ The basic procedure (get to the devmode block screen, enter reco mode, spam E while booting from RecoMod drive) will still be required to boot the system every time, even subsequent to installing it to the disk, although the 5-minute wait will be omitted

## Section V - Finished!

You are now the proud owner of a Halcyon-powered Chromebook or other ChromeOS device! Congratulations!