I don't know if it's better etiquette to semi-hijack this thread or post a new thread, but I've created the same problem for myself today. I instaled TWRP recovery successfully and downloaded a CM11 nightly along with gapps for CM11. Today I installed the zips but when my phone rebooted it started the endless LG logo loop thing, which sounds the same as he describes.
I can't seem to boot into my recovery with any key combination. Volume up and power, volume down and power, they all lead to a "Hardware Key Control Mode" menu. At this point my goal is a factory reset. Maybe the same solution that helps him will help me? I need to get the phone into either download mode or to the TWRP menu.