I mean by turning the computer on, failing to log in, then getting back to
the GRUB menu, pressing "c".
From there, you type :
cryptomount -a (press "enter")
set root='/lvm/yourvolumegroup-yourlogicalvolume' (press "enter")
linux /vmlinuz root=/dev/mapper/yourvolumegroup-yourlogicalvolume
cryptdevice=/dev/mapper/yourvolumegroup-yourlogicalvolume:root (press
"enter")
initrd /initrd.img (press "enter")
boot (press "enter")
yourvolumegroup-yourlogicalvolume
are the names given to both of these during Trisquel's encrypted install.
I assume here that you have already Libreboot and Trisquel installed, and
that you're trying to update Libreboot.