[G4 General] neutrondev:
Long story short I am in QDL 9008. I will publish all research and progress I made and in the end if I manage to unbrick it this will be a tutorial.

WARNING: Do not buy the files from Easy-Firmware or anywhere else, the emmc_firehose programmer for H815 does not exist (all of them you find on internet are wrong)

The only emmc_firehose for G4 working is the one from Sprint and it has active Qfuse!

LG G4 (H815) Partition Table extracted from the Primary GPT with gdisk:

Number Start (sector) End (sector) Size Code Name
1 32768 208895 86.0 MiB 0700 modem
2 229376 230399 512.0 KiB FFFF pmic
3 230400 232447 1024.0 KiB FFFF sbl1
4 232448 234495 1024.0 KiB FFFF tz
5 234496 235519 512.0 KiB FFFF sdi
6 235520 236543 512.0 KiB FFFF hyp
7 236544 237567 512.0 KiB FFFF rpm
8 237568 241663 2.0 MiB FFFF aboot
9 241664 243711 1024.0 KiB FFFF sbl1bak
10 243712 244735 512.0 KiB FFFF pmicbak
11 244736 246783 1024.0 KiB FFFF tzbak
12 246784 247807 512.0 KiB FFFF hypbak
13 247808 248831 512.0 KiB FFFF rpmbak
14 248832 252927 2.0 MiB FFFF abootbak
15 252928 253951 512.0 KiB FFFF sdibak
16 253952 254975 512.0 KiB FFFF limits
17 254976 255999 512.0 KiB FFFF devinfo
18 256000 257023 512.0 KiB FFFF apdp
19 257024 258047 512.0 KiB FFFF msadp
20 258048 259071 512.0 KiB FFFF dpo
21 259072 262143 1.5 MiB FFFF spare1
22 262144 294911 16.0 MiB FFFF misc
23 294912 360447 32.0 MiB FFFF persist
24 360448 363519 1.5 MiB FFFF modemst1
25 363520 366591 1.5 MiB FFFF modemst2
26 366592 369663 1.5 MiB FFFF fsg
27 369664 370687 512.0 KiB FFFF fsc
28 370688 371711 512.0 KiB FFFF ssd
29 371712 372735 512.0 KiB FFFF keystore
30 372736 376831 2.0 MiB FFFF DDR
31 376832 377855 512.0 KiB FFFF sec
32 377856 378879 512.0 KiB FFFF encrypt
33 378880 379903 512.0 KiB FFFF eksst
34 379904 380927 512.0 KiB FFFF rct
35 380928 385023 2.0 MiB 0700 persistent
36 385024 393215 4.0 MiB FFFF spare2
37 393216 491519 48.0 MiB FFFF laf
38 491520 573439 40.0 MiB FFFF boot
39 573440 655359 40.0 MiB FFFF recovery
40 655360 671743 8.0 MiB 0700 drm
41 671744 688127 8.0 MiB 0700 sns
42 688128 753663 32.0 MiB 0700 mpt
43 753664 847871 46.0 MiB FFFF factory
44 847872 868351 10.0 MiB FFFF fota
45 868352 876543 4.0 MiB FFFF raw_resources
46 876544 884735 4.0 MiB FFFF raw_resourcesbak
47 884736 9363455 4.0 GiB FFFF system
48 9363456 9887743 256.0 MiB 0700 cust
49 9895936 12419071 1.2 GiB FFFF cache
50 12419072 61046783 23.2 GiB FFFF userdata
51 61046784 61071326 12.0 MiB 0700 grow

You can compute (from a nand backup) the HEX address like this and reconstruct the partition:

1. Start Sector * 512 (and convert it to hex)

2. Size * 1024 (For KiB) or Size * 1024 * 1024 (For MiB) (this is in decimal; you can convert to hex)

About QFUSES:

As you already know some models (US variants) implement QFUSES in the QFProm for downgrade protection. Once you blow one of those fuses you are unable to revert to a previous version.

It seems that the emmc_firehose programmers on the web are for LS991 (all of them). So the moment you use that emmc_firehose programmer you turn your device into a ls991 with a blown fuse (v2).

How are those fuses working and why can't this be reverted?

As you already know all our electronics are working by lithography on a silicone wafer. On this silicone wafer there a million of transistors. By software means you can overload 1 transistor (that is normally in the off state) with a higher voltage than needed. By doing this a great enough time you will actually breakdown the oxide between the gate and the substrate and you will have a conductive channel all the time (from a logic 0 to a logic 1 or vice versa, depends on the implementation). THERE IS NO WAY TO BUILD THE OXIDE LAYER AGAIN.

WARNING: ONCE YOU USE THE EMMC_FIREHOSE THAT IS ON THE WEB YOU WILL HAVE AN LS991 NO WAY BACK TO H815!

The files here and on the internet: http://forum.gsmhosting.com/vbb/f779/unbrick-lg-g4-brick-hs-usb-qdloader-9008-without-box-2211744/ ARE NOT GOOD FOR H815!

I already tested this and indeed you will blow the fuse. I had a h815 which is rollback V0 and now I am on ZVB with anti-rollback V3.