I had a similar issue with my LG G2 back when that was the popular phone. I resolved the issue by taking the battery out for a few hours. Then, reinsert the same battery and charge it completely.
You'll want to follow the directions on the Battery: LG V20 page to remove the battery.
To this day, I'm not sure WHY it worked (perhaps it was the ritual I performed) - but it did and I'm hoping it can be applied here. after you return the battery to the casing and have left it plugged in for say, 2 hours. follow the directions on the Master reset: LG V20 page to do it using the hardware keys.
Let me know if it works (or doesn't)