Yes, you need to RMA the device if purchased from google or take it to a LG service center if purchased elsewhere. Usually a emmc brick means you can't write anything to it and that's why the bootloader state doesn't stick!
XDA Developers was founded by developers, for developers. It is now a valuable resource for people who want to make the most of their mobile devices, from customizing the look and feel to adding new functionality. Are you a developer?