Windows 10 install on new build. Please help.

[James_395]

I just finish my first build and now all I have to do is install an OS. I have Windows 10 on a USB and the pc opens up the installer when the USB is in the port once it boots up. The problem is that when I enter my key I just bought, it doesn't work so I have click "I don't have a product key", then it asks me which edition am I installing, I choose the "Upgrade" option instead of the "Custom" since that option just gives me a blank menu, and after that, I get a message saying the computer started using Windows installation media. Remove the installation media and restart your computer so that Windows starts normally. I can't do this because when I remove the USB, it just bring up the BIOS once it boots up.

 

[bicycle_repair_man]

Where did the key come from?