So that means you had no alert during the install that GRUB failed to
install?
Due to encryption (without it, GRUB get installed properly), I had to finish
Trisquel's installation without a bootloader.
So after booting, I only had a blank screen, no way to input anything. Maybe
GRUB was there hidden (I didn't know about Shift to make it appear at this
point), but I doubt it since during the install, the message was "continue
without a bootloader".
Trisquel really needs improvements in this regard. Or I just need to switch
to Debian by myself. But hey, it works for now.