OK. Looks like I made a rookie mistake. Since all the components were new including the hard drive, all I had to do was insert my Windows 10 installation DVD and everything was fine thereafter. I got to it by first creating a bootable thumb drive on my other computer (to take care of the BOOT error) and then tried restarting but this time with the Windows 10 installation DVD. So far so good
I think I have the same issue but no cd drive. Any suggestions?