After Flashing CloudyG3-2.5 LGG3 Become Unresponsive

[Usman Tufail]

Hi all, I was using LG G3 D850 AT&T. Yesterday I rooted it and installed TWRP recovery method, I downloaded CloudyG3 2.5 referring xda. In aroma installer options, I over smartly select my variant as D855. Everything went well in aroma installer without any error. Cleaned dalvik/cache etc, after that when I rebooted system my phone become unresponsive. After searching on various forums I've got no solution. I tried following tricks but of no avail:-
1. Pulled out battery and press and hold power button for 30-60 seconds
2. Put mobile on charging with battery, but no charging
3. Put on charging without battery, a yellow exclamation mark showed
4. While on charging with/without battery pressed power on for few seconds nothing happened
5. Tried to change battery, nothing happened

When I connect phone with laptop it shows in device manager but nothing shows on phone's screen. I pulled out battery and then inserted again, connected usb cable while pressed volume up key then tried to flash using LG Flashtool 2014 with stock files but it ends up with an error.
"Download FAIL!! (3 sec)"
PID: NULL
IMEI: Unknown
[17:52:50] CrossDL [Unknown] to [D850]. SWver
00000064
Error: [17:52:50] CrossDL [Unknown] to [D850]. SWver

Please help if anyone has its solution, it will be highly appreciated. Thanks