After proper reboot - Tv shows message "starting downgr8" - then fails to launch Update Checker / Firmware tool

[Qwert331]

OLED55BXPTA

OTID
HE_DTV_W20H_AFADABAA

Firmware: 04.40.18
webOS: 5.4.1

HomeBrew Channel 0.6.3
Is your device rooted: YES

Using Homebrew channel to reboot causes the USB to run, message shows "starting Downgr8" but then fails to actually launch the firmware update tool.

I tried a completely cold start - ie power unplugged for 30sec - tv booted to the USB (i could see the USB activity led going crazy, but then simply shut itself down after ~30 seconds.) also failing to launch the Firmware Downgrade Tool.

Any help would be appreciated with this issue. ; )

[Qwert331]

also, just want to reiterate the value you're creating here for people to perhaps downgrade firmware.
Personally LG have almost ruined my once impressive 2020 OLED - to be brief;
Over no less than 10 firmware updates they have

1. totally nerfed the LFE channel - when I bought it the built in sound and in particular the LFE was noticeable and quite impressive across content / media sources. ( i have had the same home theatre system with sub to make comparisons ) LFE used to be noticeable and created surprising spatial left right sound staging - not anymore. since there is NO LFE coming from it at ALL.
2. Forced HDR across streaming services, I personally despise HDR and see it purely as the marketing gimmick it really is. It literally hurts my eyes since the bright parts of the scene are always over done and i can't see anything else happening in the scene.
   Auto HDR and streaming services forcing / pushing HDR only through the tv was beyond obvious as updated firmware versions resulted in updated apps and eventually HDR on everything without the ability to switch to SDR at all. - it basically aligns with their Dolby Vision agreements yet ruins content.
3. Slow Performance, The tv has always been slow, but update after update and the shoddy / newer features are all dragging down the experience becuase its slower than ever. I luckily stopped updating on 04.40.18 allowing me to root with Crashd, but i hear the latest firmware for my telly not only changes the menu system completely but introduces a forced home screen like googles' slop that includes ads and is the SLOWEST firmware to date ! No thanks !
4. PC / DCI 4k Connectivity - So I'm running an AMD card and since the first time i used the TV with my PC it produced an excellent DCI 4k ( 4096x2160 @ 120p @ 8bit color ) picture that was absolutely flawless, with beautiful thin horizontal borders . After 10 firmware updates the card was tested on the same driver version now and the tv only connects at 3840x2160 @ 120p @8bit, the aspect ratio is not native anymore at that resolution yet there's nothing i can do (yes its a 48gbps HDMI cable ). i have tried custom resolutions and associated git programs yet my point is that on release firmware everything looked great. the worst thing about it being that i can still select 4096x2160 but the active signal resolution remains at 3840 and is abundantly obvious because of the non-native aspect ratio.
   ii) Bonus point in this category; the TV will not display a correctly placed image and always undercuts the borders by a certain amount unless 'Just Sync" is switched on; this was never a problem on earlier firmwares as the native resolution of the panel (which is DCI 4k aka 4096x2160 ) was displayed correctly and natively with the correct aspect ratio.
5. If you've read this far then congrads, basically there are other points, but man, this is just one persons story on one type of panel the BX, looking at reddit / LGOLED its abundantly clear that LG have released update after update that fails to deliver anything useful to the customer yet continues with broken features, a common issue for them but not me is eARC audio failing in various ways firmware update after firmware update but never working. Some say rolling back to earlier firmwares would be preferential because it at least stayed connected for example.

So any help getting past the "starting Downgr8" but failing to launch the firmware / update tool would be appreciated.

I tried it on a cold boot ( powered off ) the usb reads a lot for 30sec but then the panel powers down.
using Homebrew app (updated) to execute a reboot starts the USB and eventually ~45 seconds flashes the message Starting downgr8 but nothing after.

[throwaway96]

I'm not sure how you're trying to run it (why are you rebooting?), but the app isn't intended to launch the update UI. It doesn't even enable expert mode in the update service. It just makes the OS believe there is an authenticated AccessUSB connected so that enabling expert mode will work.

You need to make the Luna calls to enable expert mode and launch com.webos.app.softwareupdate yourself after running the downgr8 app (if it even works; it hasn't really been tested).

[Qwert331]

Thanks for adding some context for me;

I thought i read somewhere that the exploit only works on boot, since it was discovered that the USB would execute whatever is on it when it boots ... if it has a file named " wta_usb.sh " and that the first line must read: #!/bin/sh

I'm not sure where I read that, but anyway I thought I could get it all going by using https://phcode.dev/ to change the name of your " launch.sh " to " wta_usb.sh " - at which point it runs the code on a 'homebrew channel reboot'.

By the way, I'd like to point out that I'm grateful that you're even speaking to me ( as a lowly noob ) and that I am confident fiddling with my panel as a hobby, I believe you're responsible for the crashd method of gaining root and I thank you very much for that, as it worked for me ( OLED55BXPTA / 04.40.18 / W20H )

so basically, I could try run the USB like i have and then use SSH and the terminal tool via web-os-dev-manager to run the luna commands to boot the expert mode update tool ?

I've got a USB firmware file rather than NSU as recommended. I think i got it from webos-forums.ru - but may have also found it on the lg korea site; its labelled " starfish-atsc-secured-k6hp-147.jamestowne.k6hp-14723-03.00.55_prodkey_usb_V3_SECURED.epk "

only minor hitch is its for the ATSC tuner, im in the DVB zone ( AUS ) ; however I looked around the last archive.org listing for LG AU support page and archived / saved firmwares only go back to 03.21.75 - which I may try first as I know its exactly the correct firmware for my set - although i'd really ultimately like to go back to 03.00.55. Also I don't care if the tuner never works our free television is garbage.

Thanks again;

also it looks like the discord invites have become invalid; from the crashd instructions page.
https://discord.com/invite/xWqRVEm

[throwaway96]

The shell script is the least important part. The JS service and binary are both necessary, so you will need to build the app—i.e., compile the C program using buildroot-nc4 and package the IPK using ares-package.

ATSC firmware will not install on a DVB set. ATSC firmware may install on a DVB set, but presumably the tuner (at least) would be broken. I may be able to come up with an NSU image for HE_DTV_W20H_AFADABAA 03.00.65, but you should get as far back as possible with USB images before using it.

The Discord link works for me.

[tpaxadpom]

@Qwert331 did you ever manage to get this to work? I have rooted LG B6 I would like to downgrade FW since LG messed up the black level in the later FW builds. The same issue affected LG C6, but they provided a fix in FW upgrade.
@throwaway96 thank you for your work.