[Q] how to hard brick rooted lgg2 to have warranty topic

hi guys! i have a rooted lgg2 (d802). yesterday it dropped down and screen got crazy (it doesnt seem to be broken).i tried to restore stock rom from an old backup and know i have a system error too (lg setup wizard has stopped). Using rooted phone i lose warranty so i am looking for a way to get warranty back. Any ideas? :confused: