jamesh wrote:Have you done
sudo apt-get update
sudo apt-get upgrade
Well, yes I updated the images on the Pi 2, but apt-get is specific to Debian. I'm not running Jessie or NOOBS.
I should have said that I reviewed the troubleshooting guide and followed all the advice I could find except one bit: When I try to read the images on Windows 7, it cannot read the images (it wants to format the card), so I cannot edit config.txt. I used a tool called rufus to write the images and they work fine on the Pi 2.
jamesh wrote:If so, I would suggest a power problem.
I bought a new 2.5 amp power supply for the Pi 3 and I initially tried that (from CanaKit, it was advertised for the Pi). Then I switched to the 1.8 amp power supply that I'd been using for the Pi 2. The behavior with these two power supplies was identical. I also tried the new 12.5 watt ps with the Pi 2 and that worked fine. So, I don't think it's a power problem.
I think I was wrong in my understanding that any ARM7 image would work on the new Pi 3.