I used balenaEtcher to write Linux Mint Cinnamon to a USB flash drive successfully. When I start the computer and press F2, I can enter the InsydeH2O Setup Utility, but selecting the USB drive does not actually boot from it. Do I need to recreate the installer with Rufus or Ventoy, download a different ISO, or change a BIOS/UEFI setting?
4 Answers
In the InsydeH2O setup screen, you may need to change the boot order instead of simply highlighting the USB drive. Move the USB storage device above the internal drive using the displayed controls, often +, -, Page Up, or Page Down, then save changes and exit. Also make sure the USB is plugged in before powering on.
That message usually means Secure Boot is blocking the Linux installer. Enter the firmware settings again, locate the Secure Boot option, and temporarily disable it before trying the USB. Save the changes, reboot, and use the one-time boot menu to select the installer. If the machine is still frozen, hold the power button down for several seconds or disconnect power if necessary, then start it again.
balenaEtcher should work, so you probably do not need to recreate the USB or download another mirror. Many computers have a separate one-time boot menu key, often F9, F11, or F12. Start tapping that key immediately after powering on, then choose the USB device. The exact key depends on the manufacturer.
If Windows is still installed, its recovery settings may also offer an option to restart directly into a USB device or UEFI firmware settings. Otherwise, look up the boot-menu key for the computer's manufacturer; it is often different from the F2 key used for setup.

I tried changing the order, but then got a red 'Security Boot Fail' message and the computer stopped responding to the power button.