You can try the steps outlined in the RED warning #2 in my signature.Was trying to root new lg via drewwaltons guide, but I have the newer lcd so when I revert to V9 I lose my screen. So was wondering how to root with z4root because I cannot launch the app because I cannot see it.
Any suggestions?
You have two choices:
1) install z4root blindly. This might be difficult as there are probably many interactions you'd need to do with the touchscreen
2) run the rage exploit from adb shell. This might take multiple attempts before you get root, but it is probably easier than installing z4root blindly.
If you have another Optimus lying around, you can try doing the z4root install side-by-side so you can see where on the touchscreen to press. You could also record a video or memorize where to press.
Personally I'd try the rage method.