Thanks for your answer. I just remembered I made some Timeshift backups before I tried to change the drivers. If I rollback to the backups will I be able to try again without any consequences?

Thank you for your response! So I can select Continue boot, install Mint and then reenable Secure Boot after I'm done installing?

Thanks for the explanation! I disabled Secure Boot, though, so how did this still happen?

This was very informative, thank you! One more question: what are the differences between Mint Cinnamon and Mint Xfce?