You will need to flash the stock firmware for your model LG G5 if you can find it. I would not recommend that.Just upgraded its sw ver to v10k-505-02, which is a minor upgrade, but I wanted to go back to its original ver. (both are on 6.0.1) and I can't remember the original sw ver.
What's the best way to downgrade this?
Did you clear the system cache, or just the apps cache?
same i want to downgrade the new version is no good battery is going very fast down