How to tell if motherboard has been damaged from a fall?

Hi @dddy ,

The only way to initially tell if there may be a problem is to open the phone and to closely inspect it (use a magnifying glass if necessary) for any obvious physical or possible electrical damage that could have been caused by the fall, e.g. cracked pcb, loose components or cable connections, or “distressed” (burnt looking) components caused by non catered for circuit paths created by the fall.

If everything appears to be OK then a screen replacement (even temporary) is the only way to find out what is really happening with the phone.

Here’s a link to the ifixit LG G6 guide, which may be of some help.