MSI Live Update has managed to brick the X570-A PRO motherboard. So the R5 3600 is now installed on the X470 Gaming Plus pending recovery or RMA.
Running the BIOS recovery was useless. The CPU LED was on at all times. It seems that something serious has happened winch has left the board as unusable.
After spending $750 in the rig I am not very happy. At last the RAM is working properly. The R5 3600 does get DDR4-3200 on the X470 Gaming Plus.
After some inquiries on the phone, I was able to find the RMA submission so I could send the motherboard back for replacement.
The backup X470 Gaming Plus seems to be working so at least that problem is solved for the time being.