[G2 Android Development] KoLa_:
So, after 5 days of research, 2 numerously soft bricked phones and desperation I'm finally at LineageOS 14.1 on LG G2 D802 and ready to share the best solution that worked for me.

I'm quoting this, since it was the most useful advice. So the IOroot works only when you start from Android 4.x, according to Autoprime the 5.x was patched and the IOroot stopped working. So I needed a way to start rooting and getting a recovery from Android 5.x. After soft bricking my first phone and restoring the stock OS using this (https://xdaforums.com/showthread.php?t=2432476) method I didn't bother backing up the second device, since the data is in the cloud normally and the OS itself is irrelevant. Some things you need to know when using this method - uninstall the LG drivers that you have and install all you need from the method, don't use USB 3 to connect your phone, USB 2 is best for you. Start from the shut down phone, just hold volume up and connect the USB, then it goes into download mode smoothly and you can proceed with the clean restoration. But soft bricking aside, let's see what I had to do in order to have a clean LoS in 10 minutes (after 5 days of struggle).

You will need the following files:

1. As a rooting solution I used this: https://kingroot.net

Just download the APK for Android, get it to your phone and install it. If prompted, go to settings and allow installing apps from unknown sources.

2. As first recovery solution I used Autorec for Lolipop: https://m.apkpure.com/d802-lg-g2-autorec-lollipop/b007.autorec2

This is Autorec for Lolipop, DON'T get the Kit Kat version, since that will get you into the bootloop!

3. And I got the latest TWRP from here: http://www.gregtwallace.com/lgg2-projects/twrp/

3.1.0.0 failed for me, I used to getting black screen after the brief LG logo, but my post reached the dev and it all got fixed in 3.1.0.1.

4. Latest (or the one you prefer) build of LoS, currently I got it from here: https://download.lineageos.org/d802 (you might have a different model, so just find it on https://download.lineageos.org).

5. Since I like my Android clean of bloatware, I got the OpenGapps from here: http://opengapps.org/

For my D802 I got the ARM -> 7.1 -> Pico

So now for the workflow itself. I decided to to the cloud backup first and then start off with factory reset. Then I'd download all the files and have them ready on my computer. Once factory reset and minor Android setup is done, I'd just get the 5 files (from above) and transfer them to phone's memory. I used Download folder in the internal memory (or any other that remains in internal memory after advanced wipe from TWRP).

So, once done with factory reset, getting your clean phone back to desktop and transferring all the files are in your internal memory folder, here's what I did:

1. Find the Kingroot APK in the folder that you chose and install it from there using file explorer. If prompted, go to settings and allow installing apps from unknown sources. Once installed - launch the app, press Try root and let the app do it's work. Once done - you'll see root successful. Proceed to step 2.

2. Find the Autorec APK in the folder that you chose and install it just like Kingroot. Launch the app, grant it root permissions and DON'T DO ANYTHING. It will launch some processes in the background and start working on it's own. Once you see a big hint saying "Everything seems fine, you can flash TWRP now" only then you can press the lolipop button that says Flash TWRP. For me - if I started tapping the screen randomly before getting the Hint, the app would never show the Hint and the button would remain non-clickable, so just wait it out (preferably with an active screen).

So if the 1-2 steps didn't fail you then check one last time if you have the files mentioned in the 3-5 points above in your internal memory and if so - reboot to recovery.

3. Once in recovery, go to advanced wipe, tick all the checkboxes except for Internal Memory and proceed with it. Don't reboot. Press back until you get to main menu of TWRP.

4. Press install, find the folder where your LoS related files are supposed to be and choose to install the latest TWRP (point 3 of files you need to have from above). Once done flashing the latest TWRP, clear cache/dalvik, go back to main TWRP menu, press reboot, pick Recovery.

5. Once you're back into recovery find the folder where your LoS related files are supposed to be and choose to install the LineageOS itself. Once it's done flashing, clear dalvik/cache and go back to main menu of TWRP again.

6. Once you're back into recovery find the folder where your LoS related files are supposed to be and choose to install the OpenGapps. Once it's done flashing, clear dalvik/cache and choose to reboot to system.

The first boot takes a while, so don't panic and just wait it out. Once the system's up and you're done with the setup, you can delete the 5 files we used that are in the internal memory, since we will not need them again if everything went right.

Hopefully with this you're done and can easily upgrade your stock Android 5.0.2 on LG G2 D802 to latest LineageOS with minimalistic Gapps.

Special thanks to everyone who helped me on this journey. XDA community, Autoprime, coolhandfluke, peestandingup, Blastagator, bender_007, Kingroot team and the devs that made this all happen.