I am trying to install Debian on a new prebuilt, but when I boot and press <F2>, the screen is garbled. Windows later figures it out, but by that time it's too late to tell the BIOS to boot from a USB stick on which I've installed netinst.
The mobo is a Gigabyte B450M DS3H WIFI (rev 1.5), manual at <https://www.gigabyte.com/Motherboard/B450M-DS3H-WIFI-rev-15#kf>. I can see some letters on the garbled screen, but have not yet been able to figure out how to get to the boot order. So, either of 2 things might help me: (1) The complete key sequence at the BIOS screen (or its <F1> help screen) to tell the mobo to boot from the USB stick first. (2) Some way to boot that stick or its contents directly from inside Windows.
