CLARIFICATION: WE ARE NOT RESPONSIBLE IF YOUR PHONE ENDS UP BROKEN, DO IT AT YOUR OWN RISK, THIS GUIDE IS ONLY FOR THE LG G5 H850.
What you need:
*LG UP for LAB:LGUP_Lab_Frame_Ver_1_10.msi
* or Europe Open v10c H85010c_00_OPEN_EU_OP_0415.kdz
How to unbrick LG G5 H850 with LG UP:
Step 1, Install the USB Drivers
Step 2, Install the LG UP Software – LGUP_Install_Ver_1_14_3.msi
Step 3, Install the LG UP DLL for H850 — LGUP_H850.MSI
Step 4, Now connect your Phone to your PC Via USB Cable and Run the LG UP Software Wait until LG UP detects your Phone. If LG UP screen shows up, Go Step 5.
If LG UP can’t find your device, you need to put your phone into download mode manually by
Turning your phone off, press and hold “Volume Up” button while powering it back on and plug in the USB cable from your computer to the phone
Once your phone in download mode, run the LG UP, waiting for LG UP install necessary USB drivers for your Phone. When LG UP screen shows up. Go Step 5
Step 5, From LG UP Screen, Process option, Select Upgrade Click Bin File, Select the KDZ file you just download
And Then Click start. Wait until the step shows 100% complete, unplug USB cable, and reboot your phone.
Do NOT unplug your device till it says complete. Now your LG G5 H850 is back with Stock firmware.
XDA user @azozalawad said on a xda forum that he flashed the Vodafone branded G5 H850 firmware (V10/VD2) on his G5 (GBR) model. and it worked. See screenshots below.