Default [Q] D802 int, no download mode brick

Hi everyone,
i have D802 int. version 6 months old with stock 4.1.2 rom (one with ugly blue status bar icons). Not rooted. I try to flash new 20F kdz file with LG Flash Tool 2014 and was stuck on 27%. Flash tool ask me to try again but i did not have lucky. Now I cant go to download mode anymore. When I turn off phone completely, press vol up and then connect to usb comp. port, windows start to pop up new drives (serval in 5 sec) and ask me to format drive (phone). If i restart phone it show only LG logo and then dim screen. I cant hard reset too. Any help what to do?
PS kdz is ok.