[Essential Phone ROMs, Kernels, Recoveries, & Other] invisiblek:
LineageOS is a free, community built, aftermarket firmware distribution of Android 8.1 (Oreo), which is designed to increase performance and reliability over stock Android for your device.

It should go without saying, but do not lock your bootloader with this installed. You must be 100% stock, I'd suggest on both slots, in order to re-lock your bootloader. Doing otherwise will likely lead to a brick that Essential really shouldn't warranty.

#include <std_disclaimer.h>

/*
* Your warranty is now void.
*
* We are not responsible for bricked devices, dead SD cards,
* thermonuclear war, or you getting fired because the alarm app failed. Please
* do some research if you have any concerns about features included in this ROM
* before flashing it! YOU are choosing to make these modifications, and if
* you point the finger at us for messing up your device, we will laugh at you.
*
*/

LineageOS is based on the Android Open Source Project with extra contributions from many people within the Android community.

All the source code for LineageOS is available in the LineageOS Github repo. And if you would like to contribute to LineageOS, please visit our Gerrit Code Review.

Unofficial LineageOS Builds

Essential PH-1 (mata): https://updater.invisiblek.org/mata

Google apps

Google apps (opengapps nano) are baked in to these builds. This is due to the A/B partition layout and complications backing up/restoring gapps between builds. This is not ideal, and is the major road block to getting this device in to official status with Lineage. At this time I do not plan to release non-gapps builds. Users who require this will have to build their own.

Source

Device | Kernel

Here's a local_manifest for those who want to build at home.

Prerequisites

Unlocked bootloader

OPM1.180104.092 firmware - even if you were on this build, you should flash this firmware package to ensure the firmware is on BOTH slots.

Fastboot and ADB set up (use your google-fu to figure this out)

Installation

This device is different than what most people are familiar with due to the A/B partition layout. If you're familiar with Pixel devices, then you already know what this means. This thread isn't really designed to explain how it all works, that should be handled somewhere else. Instead, I'll assume you can either follow directions or do some research on your own. Additionally I have a discord set up where there are several people who may be able to help if you run in to a snag.

The initial install should go rather smooth, and future updates can be taken through the built-in Lineage updater app (yes, the are the seamless updates you may have heard about). Due to A/B, the recovery's ramdisk is actually on the boot.img partition (the rom's ramdisk is on the system partition now). What this means is once you flash the rom, it essentially (lol) replaces the TWRP that you have installed. This shouldn't be a problem since with the seamless updates, you shouldn't have to ever go into recovery. If you find yourself needing recovery, you'll have to re-flash TWRP to get there.

Phew, now some instructions.

See the prerequisites. You really do need these or things aren't going to work for you.

Boot into bootloader mode and wipe data with:

fastboot -w

Download twrp (mirror) and flash it with this command:

fastboot flash boot twrp-mata_11.img

(no, this isn't a typo, you are flashing twrp to the boot partition)

While still in bootloader mode, use vol down to select "Recovery mode" and hit the power button. This should boot you in to TWRP. Enter your previous lock screen password or pin (if it asks) to decrypt your data partition.

Put the device in sideload mode with:

adb shell twrp sideload

Install the zip via adb sideload with:

adb sideload <zip name here>

When finished, reboot.

Profit!

The LineageOS team would like to thank everyone involved in helping with testing, coding, debugging & documenting! Enjoy!

XDA:DevDB Information

[ROM][UNOFFICIAL] LineageOS 15.1 for the Essential PH-1 (mata), ROM for the Essential Phone

Contributors

invisiblek

Source Code: [url]https://github.com/LineageOS[/URL]

ROM OS Version: 8.x Oreo

ROM Kernel: Linux 4.x

Version Information

Status: Testing

Created 2017-11-12

Last Updated 2017-11-11