Just wanted to close this out. Thanks Loner T for all your suggestions.
Here's the bottom line. I spent a couple of hours on the phone with apple. For the 3rd time, they had me download the latest Boot Camp drivers and install. But this last time, OSX hung for many, many minutes while installing the drivers. This was like 15 minutes. I killed the process and re-installed, taking only seconds. But the next time I went to reboot, no Macitosh disk existed!!! One more boot and it re-appeared, but it won't boot. It runs about 90% of the progress bar, then the computer shuts down.
Unfortunately, this isn't the first time this has happened. The first time was due to OSX crashing after downloading the El Capitan to Sierra upgrade. Apple has a serious problem here. I hope they spend some time working on it.
In the end, I will need to rebuild OSX and Windows under Boot Camp for the 3rd time, then re-install all my tools. Each time takes about 3 days and then a couple of days to figure out all the configurations and nuances I need to fix. This time I'm thinking of making my OSX partition a lot smaller and my Windows partition a lot bigger, then giving up on using OSX for most of my computer usage.
And finally, I have no reason to believe erasing the hard drive and starting over will fix the brightness key problem. I still believe this is a bug in the drivers, at least for my 15 Pro and my 13 Pro.
Ciao!