I downloaded Windows 10 last night. Left the computer running for it to download. Had disconnection issues with internet, but I pressed the Try Again button and downloading continued. Download was finished, I had the option to install it later. I turned the computer off first. When I came back, computer works fine, still running Windows 7. Started the installation. Installation completed, had to restart to finish the upgrade. Now, the computer would not just boot. After opening the system unit, lights were on, fans, mouse, and keyboard are working. But the monitor is not displaying anything anymore. Help pls.