For anyone having this issue in the future, check that it’s not the screen (Or perhaps more spcifically, the digitizer.) I had a similar issue after using this phone for many years, the LG G4 has a double tap to wake feature that you can’t turn off, at least not through normal means. There is an app you can use to launch a ‘shortcut’ that will let you disable it. After doing that, my phone no longer woke itself up. Never fixed the actual issue, as I upgraded phones not long after, but I’d guess it was the digitizer that causes this.