I have a D852 as well. How did you hard brick it, if I can ask?
I did a quick search and it doesn't look too promising. Quite a few posts of people asking for help with a similar problem and no fixes.
There was one post I saw in the G2 section that I'll link for you and also the link to the Rogers img files. Not sure if you are with Rogers, but only found those image files.
I can't help you any further than that and not sure if it will work so don't blame me for anything you do to your phone. Best to send it back to LG for repair than attempt dive into uncharted waters. If you do find a fix though, post the results to share with others so we can all learn. Best of luck Link to G2 section with question from G3 user Rogers G3 stock partition files