LG V30 - Flash ROM using download mode? My V30 is soft-bricked because of power-loss during a system update.
Verizon would charge me a deductible for fixing it under warranty.

I can:
- Access recovery
- Access factory reset mode
- Access download / firmware update mode

I can not:
- Boot the device (shows a security warning, see my other question)
- Go into fastboot (I hold vol- while plugging in the cable, does the above thing)

I tried:
- Factory data reset (from recovery)
- Factory reset (from factory reset mode)
- Asking verizon nicely to help a broke guy under full warranty out

These all failed.

I am very familiar with adb and quite familiar with fastboot. I unlocked bootloaders before, installed custom recoveries, rooted phones, etc. - But the only time I used download mode was in combination with ODIN many years ago.

I found this ROM for my model (VS996) online, but is there any way for me to flash it without a custom recovery or fastboot?

The phone is brand new. I've never used it. It's not unlocked or tampered with or anything like that.

My direct question:

How can I flash a stock ROM on my V30 using Linux when nothing but stock recovery and download mode works? I found this but apart from it looking kinda sketchy, I need something that runs on Linux.
For linux use this link it's a tool called SALT. If you're good with Linux there are tools to use with Python such as ESPTools or LGLAF. 
For Windows  look up FWUL, it's "Forget Windows Use Linux", it's a variant of Linux build for this purpose but they were built for the older models.  


The easiest is to use LG Bridge or LG Mobile Support tool if windows or linux recognizes the phone when you plug it in as an LGE Android Net USB Serial device with a com port.  Below is the option for more tech savvy people.  

If you can get your hands on windows try LGUP.  You can google it or go the link  to download LGUP installation files (you can find them on the same forum) .  It consists of 3 MSI the LGUP Store version 1.4, the LGUP Frame and DLL. 


If you need the stock rom for your phone go to lg-firmware.com
Once it's installed, download  this patched dev version from this 
XDA post. 


It has 2 files LGUP.exe and LGUPCommon.dll. Replace the LGUPcommon.dll and overwrite the one on your C:\program files X86\LG Electronics\LGUP\model\common\ (if common folder doesn't exist create it).  Then put the LGUP.exe 2 level up from the Common folder.

Basically, put your phone in download mode first then launch LGUP.exe.  This will give you a few options to flash. 

1.Refurbished will flash then wipe your data meaning pictures and personal files will be gone.  


Upgrade option will upgrade and keep files.If you want to flash different variant/carrier chose the DL Partitions and select all do this with extreme caution because it will brick your phone.  
If you want to cross flash to unlock go on the forum you found LGFLashtool, XDADeveloper, and search for Frankenstein that's the method to root and unlock your phone.


Oh and if you chose the Refurbish or DL Parition you might lose your IMEI and serial number so either back it up first or write it down to do it later.