ladyterukiEDIT : solved, thank you !
I accidentally messed up, and enabled Secure Boot when attempting my first Linux Mint install from a USB drive. I cancelled the install, but it seems that Secure Boot might now be enabled. And I don't know how to disable it so that I can retry my Linux install.
(See https://mastodon.social/@ladyteruki/116561155237730457 )
Now I can't boot from the USB drive anymore, and my screen looks like this ?
