[Essential Phone ROMs, Kernels, Recoveries, & Other] Syndrome666:
I'm sure most of you got this working by now, but for those still having trouble, what may be unclear is that after you factory reset/format (fastboot -w), DO NOT swap to slot B! Formatting sets slot A as the default slot. At least that's what mine did the numerous times I I executed ./fastboot -w command after setting it to slot B manually.

Assuming you have adb/fastboot setup on desktop/laptop and device has an unlocked bootloader, here's the full list of steps including their slot states:

Step 1) If coming from a different ROM or simply unsure

In fastboot mode, wipe/format through terminal/command prompt:

./fastboot -w

This will format the device and reset the slots with slot A as the current slot.

Step 2) ./fastboot flash boot twrp.img

From the device using volume and power keys: reboot to recovery (TWRP will boot)

**Current-slot A**

Step 3) Place all the necessary files (ROM zip, Gapps zip, Neutrino boot/kernel image, and Magisk.zip) into the platform-tools folder on your computer.

In terminal navigate into platform-tools directory:

cd /platform-tools directory path

./adb push "name of file" /sdcard

Push all 4 files to /sdcard directory on your essential phone

**Current-slot A**

Step 4) On the device, select Install from the TWRP menu, navigate to /sdcard (or wherever you placed your ROM)

Flash the ROM

wipe cache/dalvik (it'll complain about cache partition, just ignore that message as it doesn't apply to this device's partition structure).

**Current-slot A**

Step 5) Go back to main TWRP menu, select reboot and boot to bootloader (don't touch any of the slot buttons, just select bootloader from the reboot menu screen).

Once it reboots back into bootloader:

**Current-slot B**

Step 6) Back to computer, in terminal flash twrp again

./fastboot flash boot twrp.img

and reboot to TWRP using phone

In TWRP, Install Neutrino kernel image (you'll see install from zip button at the bottom right, press it and change it to install from image), wipe cache; dalvik, then (switch back to zip) install Gapps zip.

**Current-slot B**

Once complete, wipe cache/dalvik and reboot to system (again do not mess with slot A and slot B buttons)

Set up the device however you like (as new or a restore from Google cloud or another device)

Step 7) Reboot to bootloader and connect phone back to computer (if disconnected).

On the computer, cd back into platform-tools directory and flash twrp image again.

Boot into TWRP from device

Select the Install menu from the TWRP main menu

Switch to install from image and flash Neutrino kernel image again, wipe cache/dalvik

Switch back to install from zip and flash the latest Magisk zip (stable recommended for optimal function)

Step 8) Reboot system

If you followed this guide, you should have no problems getting this running, if not, return to step 1, rinse and repeat.

*Windows users leave out ./ in command prompt window when using fastboot and adb commands. You may also need to download drivers from Essential's page for this device to register with your windows machine.

Thanks to [MENTION=4675246]Ashwin Prabhunerurkar[/MENTION], [MENTION=3462598]BakedTator[/MENTION], [MENTION=4412634]Joylesstuna[/MENTION], [MENTION=6901005]MoistPicklez[/MENTION] for helping me get this ROM working.