I have reprogrammed the SD card using a different PC and SD card adapter. It has been happily blinking away for about 15 minutes. I expect it will complete as expected.
So I’m pretty sure the problem is with the SC card adapter I was using. It was an older Spyker USB Hub and multiple format flash card adapter. I’m surprised that so much worked right but the rootfs was still corrupted. I also got no error messages from the Win32DiskImager utility using this adapter.
Oh well, on to better things. At least I learned a lot about the boot and flashing process while chasing this down.
Thanks for your suggestions and taking the time to check the MD5 checksums.
Dennis Cote