https://youtube.com/watch?v=WjABILVAz5Y

The channel is called Blind.

You’re right. /dev/sda1 is the efi partition for the hard drive. I would still be interested in the output of lsblk -f to see what it says about the file system type.

It looks like /dev/sdb2 is your efi partition. Your disk names probably got swapped. It might be worth to switch to UUIDs. lsblk -f gives you your filesystem types and UUIDs for your partitions.

Edit: This is incorrect.

The login screen is handled by the display manager (DM). Linux Mint Cinnamon (not sure if you’re using that) uses lightdm with the slick greeter by default.

Here are two links with different solutions:

https://wiki.archlinux.org/title/LightDM#Multiple-monitor_setup you can get the settings you have from running the command xrandr without any options or using arandr as described in the other link.

https://forums.linuxmint.com/viewtopic.php?t=360800 Here I would tweak it a bit and not use chmod 700, but instead use chmod 744.

Can you give a little more background info? What distro are you using, are you dual booting, is it a new install, did you make changes to your kernel, your partitions or grub before that?

While it’s clear that grub couldn’t find a kernel to boot, we need these Infos to help you find a solution.