UnSecUred, I'm not sure if you are still having this issue as this thread is months old, but I was having the same exact issue with my lg lucid 3, after a bit of digging I was able to find the stock firmware from some shady parts of the internet
be sure you have the right usb drivers installed and that you place the kdz file in the same director as the flash tool, be sure to read the directions in the thread. Also you place your phone in download mode this way