I have recently had to install Windows 7 on a computer that was manufactured for secure boot and for Windows 8 and above.
I used the the Windows7-USB-DVD-Download-Tool-Installer-en-US.exe from Microsoft to copy the Windows 7 x64 iso to a USB key and tried to boot the computer and no matter what I did it refused to boot into the Windows install.
I found that you have to go into the BIOS and turn off (mark it as ‘disabled’) the “Windows 8.x” logo install option (or something similar) which would then revert you back to the ability to boot Windows 7 installation media.
The next hurdle was when the Windows 7 Pro SP1 Installation Media USB Key booted I suddenly lost my USB keyboard and mouse.
This required me to download from MSI the Win7_Smart_Tool.zip utility in order to make an install image that included the correct drivers for the USB Keyboard and Mouse. I unzipped and ran this and pointed it at my ISO mounted as a drive letter and then tried to get it to create an install USB Key. This failed. I had to create an ISO on the hard disk. And then once I had the Win7_Smart_Tool created ISO which includes the correct drivers for the USB Keyboard and Mouse to function. The utility may have failed to directly create the Install Media USB Key because I was in a Windows 10 VM running on my Macbook but in the end I created the MSI specific install ISO on C:\ and then pointed Microsofts Windows7-USB-DVD-Download-Tool-Installer-en-US.exe at it to complete the ISO copy to the USB key.
So finally I could install Windows 7 on the PC.
But sadly that is only the beginning of a marathon driver download session https://www.msi.com/All-in-One-PC/support/Pro-20E-4BW.html#down-driver&Win7 64 another couple of hundred megabytes of drivers and I finally had a working install.
Anyway put this on the internets in the hope that it is useful to someone.