If reinstalling the O/S didn't help, it seems a clear warranty issue. Ask for an exchange.
This phone randomly changes the date and time - usually backwards. This problem has been ongoing since I purchased it. It has been back to LG for a re-installation of o/s. I have tried using every possible option of the Automatic date and time, the Automatic time zone, setting the date and time - but still it changes randomly. Any suggestions?