To boot your LS676 in download mode.
Turn off the phone
Connect USB Cable to phone
Press the volume up key.
Keep it pressed, and connect the other end of USB cable to the computer.
Now your phone must be in download mode. It would read “Firmware Update”.
Now run the LGUP program. It’ll show the connected phone model and its current firmware version. In my case, it’s showing LS676 ZV3, even though I’ve already updated the phone to ZV4.
Click on 3 dot icon below “File Path” to browse for the downloaded TOT firmware file.
Select the “LS676ZV3” tot file and open it in LGUP.
You can see the firmware file is now showing up in “File Path”. We’re now ready for flashing.
Click on “Start” to begin the process. Don’t unplug the cable till the process gets completed.
The phone will reboot on its own when the flashing gets completed.
It’s recommended to perform a factory reset after the flashing is done.