How can I unbrick my LG G2?

[AC Question]

Bricked Lg G2

Hi there! I'm a stupid-stupid person. I was trying to get Lollipop faster, so I tried to flash lollipop on my phone.
I managed to root it, but haven't done any backup, except for media and contacts.
I'll try to explain what I've done.

So I rooted the phone, entered the download mode and then I tried to flash it using LG Flash Tool 2014.
When in download mode, it was stuck at 0%, so I didn't wait to go ahead, I tried to flash it.
Now, the flash failed several times. The phone was alright then.
Further, I tried again and at some point something happened, it got to two percent, it wrote COM4 and then it failed. It might have been my antivirus that stopped the process, I'm not sure.
Well, now I have a useless phone. It keeps showing the LG logo.
The hard reset doesn't work, it's not recognized in Device manager, and it doesn't work download mode.
When I try to power it off it does so only after a long press. At first, when the screen goes black, if I release the power switch, then it will reboot again. If I press it long enough, the phone will power off.
I'm desperate, of course.
The phone was running Kitkat.