I’m betting this is a Secure Boot issue.
Secure Boot is enabled by default, and Windows 7 is pre-Secure-Boot, so you’ll need to disable Secure Boot in the BIOS before it’ll want to boot off that install media.
See the BIOS guide thread for more details/screenshots, but in summary, F2 during startup (press it a bunch when the screen is on but blank or framework logo is there) to get into the BIOS settings, “Security” tab, then “Secure Boot” sub-heading, then set “Enforce Secure Boot” from Enabled to Disabled.