The power reset procedure as instructed in that Sony link did not repair the problem that I had with my TV. The overnight reset procedure that I mentioned corrected the problems that I had.
If that procedure did not work, I am not sure where I would have started troubleshooting. No trouble codes, and only the bottom 10% of the screen had a picture.
Lucky for me the TV works as new with the overnight reset.
I did a partial factory reset before my final overnight power reset, so I had to complete it once the TV was working again. The picture froze during the factory reset, so I could not complete it the first time I tried. I had to remember the procedure on how to access my wireless router from the TV. That took the most time. The Rovi program guide requires internet access, as does all forms of video streaming.