[G4 Q&A, Help & Troubleshooting] Patross2:
Hello, I would like to first tell you the story my LG G4 has gone through and then I tell you the error.

So, at first my phone was working absolutely properly. I accidentally deleted some pictures and to do a recovery, I had to root it. And rooting would be useful for later so why not do it?

So I first unlocked the bootloader through the code from the LG site. After unlocking, the phone reset (because it would be just too good to make some memory changes and nothing more.) But allright. Then I was ready to root. I just booted the phone, everything was fine. I unlocked the developer mode and opened ADB. I rebooted to recovery through

adb reboot recovery

I was expecting to see some menu with buttons (but that would be just too good). However, I saw just android with a red triangle in the middle. Nothing more. No response to buttons, nothing.

So I thought. Allright, let's boot into recovery using hardware buttons (vol down + power) at startup. Unfortunatelly, it seemed like there is no such mode System just normally booted (and that was just after bootloader unlocking. Recovery mode goodbye.).

I tried to send commands to the phone using diagnostic port. Unfortunately, it responded by FAIL to every command.

I reboot to bootloader and booted an image: "boot-em.img" (from here: google: how-to-root-lg-g4-on-android-6-0-marshmallow-20a20b-firmware. I'm a newbie here. thx for understanding.)

After that the console uploaded the image and booted successfully. Then, however, system started to boot up and was endlessly booting (LG boot animation) till the battery was critical.

I was able to access the EMI number through volume-down button and volume-up button pressed simultaneously.

I was also able to access some factory-reset dialog by holding volume-down and pressing power-button several times. I choosed to reset everything and then accepted it with one more 'are you sure dialog'. System rebooted and was stucked in the LG boot animation.

Then I got to download mode, since recovery mode was lost in hell. Through LG-UP I flashed the original KDZ firmware and everything got back to normal, but recovery mode was still inaccessible through the hardware buttons. I got through the process of setting everything up, getting developer, rebooting to bootloader and I booted TWRP.

TWRP loaded and it responded to double-tap on screen to wake it up. I just checked the menus and let the phone sleep.

After several hours I went back to the phone and double-tapped on display. Nothing. Phone was not responding. I pressed the power button and the phone restarted (I think. It either restarted into the system or was not responding to power button.)

So I got to the system and again rebooted to the TWRP (through fast-boot). I tried to back-up one partition to the disk. During the process phone had turned the display off. So I double tapped. Nothing. I removed the SD card and the phone woke, saying that back-up process was not able to complete. Suddenly it stopped responding to double-tap. It woke up through an interrupt. I re-inserted the card, successfully backed-up the partition to the SD-card and I left the phone laying on the bed plugged in the charger. It stayed that way for 4 hours or so, doing nothing. All of a sudden, a yellow screen was there, (and that's a screen of absolute death that was never supposed to come. Little I knew.) saying that an unexpected critical error happened and to do a memory dump, insert a cable, set up some communication (I don't remember what it was, didn't take a picture of it.) and it could send the memory dump to PC or somewhere. I thought to myself. So, the application is not so stable after all. It said that to reboot just press the power button or something.

And now the problem comes:

The first start: Bootloader booted, LG animation went on and finished. The starting up apps dialog came rolling. Then, system restarted.

The restart: Bootloader booted, LG animation went on and freezed. Then, the phone restarted.

Second restart: The same thing as the first one.

Fourth restart up till now: Bootloader tries to boot and restarts before the LG animation.

I got to download mode and it restarted even there. After re-inserting the batterry I can sometimes get to the Firmware Update window and communicate. There I flashed the official firmware again.

No success, as if I didn't even do it. It restarts before the animation.

Can I do anything with the phone? Hopefully I can. No hardware problem occured (except for a situation where the error could fry the wires inside the mighty System On Chip.)

For the software state I cannot even tell but I might say it's cooked just wrong. That's why I came here.

I know I did some pretty stupid steps. But the error was not done by me. It worked fine and after the yellow screen which came by itself, it just (some bad words).

Thanks for replies.

Phone: LG-G4 H815, European market