In the GRUB boot menu (the first screen you see after booting from the USB), select Start Linux Mint (compatibility mode) . This uses basic video drivers to ensure a desktop appears.
A black screen when booting a Linux Mint Live USB is typically caused by graphics driver conflicts or BIOS/UEFI security settings . Immediate Workarounds Linux Mint Live Usb Black Screen
If compatibility mode isn't visible, press e at the GRUB menu to edit the boot entry. Find the line ending in quiet splash , add nomodeset after it, and press Ctrl+X or F10 to boot. BIOS/UEFI Setting Changes Live usb boots on black screen. - Linux Mint Forums In the GRUB boot menu (the first screen