On your LG V40, go to Settings > Developer options and enable USB Debugging .
Keep holding Volume Up until you see a screen with a small image or text saying “Download Mode” (or a firmware update screen). How to Open Download Mode on LG V40 ThinQ
Download Mode (often called Firmware Update mode) is a low-level state on your LG V40 that allows you to flash stock firmware, unbrick the device, or perform system repairs using LG's official software (like LG Bridge or LGUP). On your LG V40, go to Settings >
Install ADB and Fastboot on your computer. On your LG V40