Chosen Solution
I unplugged the Playstation and then plugged it back in–just red light. Then I inserted a Bluray disk and the machine turned on. Screen message: “Cannot start. The correct hard disk was not found.” Nothing else was going on, i.e. no updates, nothing. I did the unplug because Netflix would not load and I thought a reboot could fix that problem. I am very new to this unit–it belongs to my son-in-law–and all I use it for is Netflix movies and Bluray discs.
I left the PS3 off overnight, then removed and replaced the hard drive, being careful to blow away any dust. Then I restarted the machine using the front switch and voila, there was a working PS3!