[General Questions and Answers] GuiRitter:
Hi everyone.

I purchased a new Motorola Moto G6 with the intention to try out using LineageOS instead of the stock rom.

Here's everything that used to appear in the About section of the Settings. Keep in mind I selected Portuguese so I'll be translating some labels:

Software channel: retin

Android version: 8.0.0

Android security patch level: 2018-04-01

Base band version: M450_03.08.10.51R ALI_INDIADSDS_CUST

Kernel version: 3.18.71-perf-ga4749e5

hudsoncm@ilclbld32 #1

Fri Mar 30 11:53:22 CDT 2018

Version number: OPS27.82-45

This is my first time messing with phones like this. I am a Computer Engineer, though.

I started following the instructions here. I enabled developer options in the settings, enabled USB debugging and allowed OEM unlocking.

Then I unlocked the bootloader. I'm using ADB and Fastboot that came with Android Studio.

I ran fastboot oem get_unlock_data, got the code, inserted in on the Motorola website, got the email with the unlock key and unlocked it with fastboot oem unlock UNIQUE_KEY.

Then I installed TWRP 3.3.1-0. No problems there.

Then I had to search for the link to download LineageOS and GApps because it looked like the steps I was following were incomplete.

I downloaded LineageOS from here and GApps from here. For the latter, I chose ARM64, Android 10.0 and full. I transfered them to the internal storage using Android Studio Device File Explorer.

Then I followed the YouTube video from the first link. I had trouble wiping because of encryption, so it seems. I followed this to proceed. Using a pass or a pin didn't work. The next solution, Repair File System, was unavailable. I could only see Change File System. Then I formatted /data to EXT2 then back to EXT4 and it worked.

Then I tried to flash LineageOS. I got error 255. I looked here. Apparently, I should have used a 64 bit TWRP. I found one here and flashed it. Then I was able to flash both LineageOS and GApps. No error messages here.

Then I rebooted without installing the TWRP app. I got the following:

Start Up Failed:

Your device didn't start up successfully.
Use the Software Repair Assistant on computer
to repair your device.
Connect you device to your computer to get
the Software Repair Assistant.

AP Fastboot Flash Mode (Secure)
Error: failed to load kernel!
Fastboot Reason: Fall-through from normal boot mode
USB connected

I searched and didn't find much. I looked for the Software Repair Assistant but it seems it's only good to reinstall the stock ROM. I still want to install LineageOS, though.

I found some results about flashing boot.img and some other stuff, but I'm too afraid to hard brick my phone to follow any instructions that haven't been written specifically for my situation.

I still can access TWRP. I wiped and installed again to double check that there wasn't any error messages during flashing and then again to try installing the TWRP app, but the prompt for that didn't show up.

Please advise on what to do to complete installing LineageOS on my Moto G6.

Update 2020-12-15: It seems that the tutorial I followed has been updated. Now there are no steps missing. I'll try again using the files provided there.

Thanks in advance.