I have some questions.
1. whats the model variant of your LG Optimus G Pro ?
2. Did you tried flashing a cynogenmod with a Custom Recovery or ?
The reason for asking the 2nd question, is because, it seems impossible for me to access the Factory Stock Recovery (Android System Recovery 3e) on e980 version and I only get a black screen and a blinking home button.
adb reboot recovery
but now it's giving me security error(it doesn't boot up) and I cant access recovery that way... also I cant get into download mode by holding down both volume keys and pluging in USB.