I have read a lot on this problem and seems no one really knows what is causing it. The reason I ask is I use pre-owned phones and just upgraded from a LG G2 to a LG G4 and like the G2 the G4 is working great. This is the best phone I have had. I was thinking about rooting and installing a new rom but I think l will wait. ( G4 has s/n 505, and made 05/15 )