I've got the Windows.iso file on the new hard drive,
Sorry but this needs to be on a USB thumbdrive so that if an in place update does not work you can then insert the USB device into a USB 2.0 port and clean install from there, having saved the ISO to a HDD you would need to burn it to a DVD disk before being able to use it, you need the portable USB device option so that it can be used on both computers.
After fifteen hours of doing nothing something is clearly amiss
Use option two here to put Windows 10 on an 8GB or above USB thumbdrive then get back to us.
NB: Can I just make sure that you have any product keys safely written down.