Don't worry... still no cable!
My 3 year old, 50" LG plasma TV just decided to go black one day. We still had audio, but no picture whatsoever. I jumped on the Google machine and set to work. I discovered that an LG plasma TV crapping out after 3 years is pretty common, and having one last to 5 years is notable. I also discovered a bunch of troubleshooting information that involved removing the back of the unit and systematically unplugging and replugging circuit boards.
For those of you who are interested, it turns out the lower buffer board was fried.
For those of you who aren't; it cost me $91 to have the replacement part shipped to me from New Zealand. I also got all the nice feelings of accomplishment having conquered the problem myself, so it's all good.