There are several backlight led power lines in LG V10 going from motherboard to display through the connector. You can tell if it's just a backlight problem by by shining powerful flashlight and checking if any image is present. Most likely LED is not getting power and this could be due to filter capacitors tied to LED power lines being bad or PMI chip which powers the LED being bad. So approach would be to identify the filter capacitors, test the filter capacitors for short and then replace PMI chip if necessary. Of course, with LG V10 already being 9 years old, it's not worth the bother unless someone is doing this for fun and hobby.