[Q] Rom install failed now can't boot topic

Hi guys, so my problem is I was installing a new rom on my rooted D855. everything was going along fine but then the process stalled. I left it running for 15 - 20 minutes but it was still on 33%. I tried holding the power button in desperation which shut the thing down. Now when I try to factory reset it goes to the prompt screen, I answer yes, then it asks me to confirm. from there however it goes to LG splash screen and eventually a black screen with Fastboot mode started. -reset- portcharge -reset- portcharge fastboot: processing commands in the top left corner. That's it.. If I try download mode it goes to the download screen and then to the black screen as described above.
Sounds pretty ordinary but if there is an answer out there I am sure one of you guys will know it.
TIA