Odin Downgrade to 4.4.2 Fail - Verizon Galaxy S5

[gml213]

Hello, I know this question's been asked countless times, but most fixes I find never never seem to work.
I've been trying to Downgrade my Galaxy S5 running 5.0 back to earliest version of 4.4.2 available for the phone so that I will be able to root with Towelroot.

First, I'll give some info:
Model: SM-G900V
Baseband Version: G900VVRUBOG5
Kernel Version: 3.4.0
Build Number: LRX21T.G900VVRU2BOG5
Hardware Version: G900V.05
KNOX 2.3

I downloaded the 4.4.2 firmware for the G900V from Sammoblie,
G900VVRU1ANCG_G900VVZW1ANCG_G900VVRU1ANCG_HOME.tar.md5

Using Odin version 3.09, I selected AP and then the firmware file, put my phone in download mode, connected, and got the usual blue icon meaning Odin sees my phone.

When I press start, the download fails almost immediately, after the status bar says ABOOT

Here is what happens in the message box:

<OSM> Enter CS for MD5..
<OSM> Check MD5.. Do not unplug the cable..
<OSM> Please wait..
<OSM> G900VVRU1ANK2_G900VVZW1ANK2_G900VVRU1ANK2_HOME.tar.md5 is valid.
<OSM> Checking MD5 finished Sucessfully..
<OSM> Leave CS..
<ID:0/007> Added!!
<ID:0/007> Odin v.3 engine (ID:7)..
<ID:0/007> File analysis..
<ID:0/007> SetupConnection..
<ID:0/007> Initialzation..
<ID:0/007> Get PIT for mapping..
<ID:0/007> Firmware update start..
<ID:0/007> SingleDownload.
<ID:0/007> aboot.mbn
<ID:0/007> NAND Write Start!!
<ID:0/007> FAIL! (Auth)
<ID:0/007>
<ID:0/007> Complete(Write) operation failed.
<OSM> All threads completed. (succeed 0 / failed 1)

Any ideas for how to make the download work?