Four workarounds. Two require unlocked bootloader. If none work for you,
1) make sure you are on the correct Dev Patched LGUP from this thread. (See post #2 for Dev Patched LGUP and follow the installation instructions. Uninstall any prior version of LGUP.)
2) Look over these steps again, make sure you followed them all. Do NOT skip steps!
If it STILL doesn't work, there are no more answers after this. Just flash back to US998 Oreo 20h wait for the next US998 Pie KDZ.
RECOVERY TIPS if you get stuck on logo while updating to this wonky US998 Pie. < Please stop asking in Telegram thread or creating new XDA threads when it's right here. We will just direct you back here. OK?
4 WORKAROUND METHODS TO SUCCESSFULLY UPDATE TO US998 PIE FOR THOSE PEOPLE GETTING STUCK ON ThinQ/ LG LOGO
METHOD #1 -- WITH OR WITHOUT UNLOCKED BOOTLOADER
I've been reading reports from other LG models (like LG G6), where LG has LG Bridge downgrade the phone back to Nougat first before then updating to Pie. LG Bridge uses full image KDZ, temporarily downloaded to PC.
So I suggest trying to Partition DL back to Nougat KDZ, Master Reset, then Partition DL to Pie KDZ. Here are the steps...
0) Using Dev Patched LGUP from this thread, REFURBISH back to US998 20h. Turn off phone, go into Download mode.
1) Flash US998 10d Nougat KDZ via Dev Patched LGUP using Partition DL mode. Select ALL partitions.
2) Master Reset. This is NOT Factory Reset.
3) Boot up to Welcome screen. Turn off phone, go into Download mode.
4) Flash US998 30b Pie KDZ via Dev Patched LGUP using Partition DL mode. Select ALL partitions.
5) Master Reset. This is NOT Factory Reset.
- If you did not unlock your bootloader before doing this, then you bootloader is still locked -- because that's what you want. Finished. Set up your phone.
- If you had unlocked bootloader before doing all this, you will still have it. Boot to ADB, and PLEASE follow these instructions for re-install TWRP and root!!
This next method by @EstebanxZ uses parts of #1 & #3 (oldest method which works). I'll will rewrite when I get time, but right now just quoting verbatim what worked for him:
METHOD #2 -- NEEDS UNLOCKED BOOTLOADER
This third below is our oldest method which works, but is most complicated.
METHOD #3 -- WITH TWRP
We have a working method for people with TWRP who are having trouble getting across the line for Pie. Most people have no problems updating. I didn't. However, for those who are having issues, there's a workaround, but you need TWRP installed and make sure you're using the Dev Patched LGUP from THIS thread. (See post #2 for Dev Patched LGUP and follow the installation instructions. Uninstall any prior version of LGUP.)
For users with TWRP who get stuck on ThinQ/LG logo:
0) Using Dev Patched LGUP from this thread, REFURBISH back to US998 20h. Flash TWRP recovery via fastboot. Turn off phone, go into Download mode.
1) Flash Canada H933 10h Nougat via Dev Patched LGUP using Partition DL mode -- EXCEPT for Recovery partitions, to keep TWRP. Do NOT choose "all" partitions! Omit/UNcheck the Recovery partitions.
Reboot. You will probably have lost download mode, but you've prepped your phone, corrected any partitions -- and you still have TWRP.
NOTE: For the next step, you will need to use the much-hated "hardware button dance" to boot to TWRP custom recovery, since H933 firmware doesn't have fastboot flash commands to boot to TWRP from PC. You also no longer have root at this stage, so you can't use the excellent Reboot Recovery app or NOXX Advanced Power Menu app...
You will need to IMMEDIATELY start the "hardware button dance" just time phone reboots. This is the ONLY time I will ever tell you to use the "hardware button dance". Any other time, it's stupid and ridiculous and there are better ways to boot to TWRP custom recovery.
2) Flash US99820e TWRP-flashable zip to get back Download mode. (Remember you KEPT TWRP recovery partition!) IF it doesn't boot, make sure you are on Magisk 18.1. Oreo TWRP-flashable zips normally require Magisk 18.x.
3) Then REFURBISH to US998 20h KDZ.
This will temporarily wipe out TWRP, but give you a completely fresh install. You will still have unlocked bootloader and fastboot flash commands.
4) Now flash TWRP recovery again via fastboot flash commands and then flash the US99830b Pie TWRP-flashable zip. See Section 6 of the WTF instructions if you need to remember all the steps to install TWRP, etc.
"Phone booted immediately on pie and everything is working great." - TESTER
You are now on US998 30b Pie!
After all that you can flash to other compatible TWRP-flashable zip if you wish.
METHOD #4 -- WITH OR WITHOUT UNLOCKED BOOTLOADER
Thanks to @SaiLas:
I have a strange problem. I flashed US99830b using LGUP Partition DL. My phone was stuck on the boot screen then, so after a lot of tweaking around in TWRP, which included trying to flash the TWRP flashable ROM of Pie. But it didnt work either. So I tried to return to Oreo US99820h but phone just wont boot to Download mode. I did Power up and plugged in USB, the four blue dots showed up, but then instead of entering download mode, the phone rebooted. Somehow reflashed US9980h through TWRP, but the phone still wont enter Download mode. It just reboots halfway through the process. Help please.