lg g3 screen unresponsive after touch firmware upgrade

[mviktors]

I have a lg g3 d855, after going to the service menu and attempting a touch screen firmware upgrade my phone got stuck and now my touch screen is dead. I tried several solutions, flashing .kdz through lg flash tool, upgrading my firmware through lg mobile support tool etc.

For the last two days I tried everything I can, so I'll try to explain every move I made. First of all, I tried every version from kitkat to lollipop, even I flashed the marshmallow update, but no success. ATM I am on lollipop stock rom, with root and TWRP recovery. I am using my mouse through usb adapter to navigate with the phone. I rooted my phone with kingroot app.
- The touch screen firmware version on my phone is -1, that was the case even before my screen got unresponsive, I can't figure it out how is this possible. I tried doing the same thing, updating the touch screen firmware but nothing happens when I click update through the service menu.
- I opened the back of the phone, reconnected the screen with the motherboard and turned on the phone - but no success. The situation remains the same. unresponsive screen.
So I am kindly asking for any advice or idea you have about my problem, how can I get my phone to work properly?
Does someone know where can I find a working touchscreen firmware for LG G3 D855? Is it possible to push the firmware to my phone using adb sideload or twrp?
At last, can a screen replacement solve this issue? I am 100% sure that this is not a hardware problem, all I need is to push a touch screen firmware on my phone.
Please help!