Are you using Windows?
What you can do is use the android sdk to issue fastboot commands to the phone in order to restore download mode. At that time, you can use LG Flash Tools and the vs980 tot/bin files to reflash the stock firmware.
If you are in fact on Windows, you can use
Koush's Universal Driver in order to use adb/fastboot.
If you don't already have the sdk set up on your machine, you can use our forum's
Mini SDK instead as it's far easier and faster to set up.
Then to test for a positive connection to the phone, open the command prompt, change directory to the sdk-tools folder and enter the following command:
fastboot devices
If it shows the phone's s/n, you're good to proceed.
Download the laf and aboot partitions from
HERE. (thanks to Autoprime)
Rename them to aboot.img and laf.img and place them into the sdk-tools folder.
Then flash those two partitions to the phone to restore download mode using these two commands:
fastboot flash aboot aboot.img
fastboot flash laf laf.img
Exit command prompt and press and hold power on the phone until it shuts off. Then press and hold volume up while at the same time plugging the phone into the USB cable in the PC. If you get download mode, you're good to use LG Flash Tools to reflash the stock firmware.