[G4 Q&A, Help & Troubleshooting] Lilrock:
Greetings,

General

I've been all over the Internet trying to gain access to more information about how to repair my LG G4. Well... Let's start from the beginning.

Story

I have an LG G4, it's old and I've had it for over 4-5 years now... I can't exactly remember how long I had it for. It still works, just needs a new battery and cable (cats chewed the cable and batteries don't last when you forget to disconnect them from the device, leave it plugged in for weeks and let it completely die for longer then a week).

I recently saw a video about the Pine phone and the fact that it was able to run a linux mobile distribution and when I looked into installing a custom OS into LG G4, it was possible... If I manually ported it myself.

I actually got fairly far using my Xubuntu system with configuring and compiling, the trouble I ran into was that I couldn't root or fastboot my device.

So, now here's where the problem began, I have a LG G4 factory reset and when I load up the Recovery mode, it brings up the android guy with their chest open and an exclamation mark in a yellow triangle, no message. After attempting to boot into recovery mode, I wait a little while and the phone automatically resets back to normal. When I use ADB to force the phone into fast boot, it skips it and starts the phone normally.

Now I'm on a mission to find a way to either fix the boot or flash the firmware (in hopes that it fixes the boot/recovery).

I have already tried:

Installing LGFlashTool

Versions, 2.0.1.6, 2.0.1.9, Year: 2014 and 2.0.2.5. Other than year 2014, the other ones were installed from LGFlashTool.com

Since Xubuntu can't run these files properly, I just ran them on my wife's Windows computer

I installed the LG Mobile Drivers and LGFlashTool had registered that it was the correct DLL but, it didn't seem to find the phone

Year 2014 LGFlashTool had found the phone but, I may have had the incorrect kdz file.

The Flash starts and the phone goes to firmware update, but the phone stops at zero and sits there while the program crashes saying that there was an error (in which no means to read, understand or locate the description of this error) and to try again by unplugging and removing the battery.

This version was downloaded from xda-developers.com

Conclusion

Once I can get into fastboot, I'll be able to root my phone and attempt to install the mobile OS I have ready.

Otherwise, I think I might be able to install a microSD card with the OS but, I don't think that will work if I can't get into the option to boot from a separate location (I believe that's called fastboot). But, then again... I think the phone needs to be rooted first... Then that brings me to the previous issue.

Details and Information

The phone details (as far as I see) are:

When I remove the battery I can see:

FCC ID: ZMFH810

IC ID: 2703C-H812

Model Number: LG-H812

I'm not exactly sure what KDZ file I got but the name is: PR H810PR10a_02.kdz, I also have the _04.kdz

I'm using H815 as my compile for the mobile OS, I may switch to H810 when I get back to that point.

Useless information: I still have the original leather backing... Removed from the phone because I didn't like it. If I find it, I can ship it to someone.

That's about it... I am very terrible about research and using Google properly (I have no idea why, I think it's a terrible flaw to have but, I have it). So, if you find the solution by typing words I didn't use or finding a similar post, I am very sorry. Hope I have everything posted here to help solve the issue, linking to posts that can resolve the issue or posting questions on what I might be missing will help.

Thanks in advance for the support of this community,

Lilrock