As with most people I experienced the same issue (Elementary OS 0.3.1 not loading grub menu or booting the operating system). 1) Install (or update to) Elementary OS 0.3.1, if you haven't already. 2) Start your computer. You now see the black screen with "grub>" 3) Check when your gub.cfg is located. Type "ls" to see all your partitions, Mine was in: Code (Text): ls (hd0,gpt1)/ 4) Assuming it's on (hd0, gpt1), type: Code (Text): configfile (hd0,gpt1)/efi/grub/grub.cfg 5) You now get the grub boot menu, choose the first one. 5.5) Note: If you have full disk encryption, you will be asked for your password in a strange way (it looks like something is wrong, but somewhere in the lines of text up there it says to enter your password, just type it). 6) Elementary OS is booted (Note: if you get a black screen, either this is due to the acpi issue or just press or button or two and it's visible (my case), or CTRL+ALT+F1 and then CTRL+ALT+F7, otherwise acpi issue, in this case, restart again and get back to the boot list menu, like step 5, but press e and add "acpi=off" after splash) 7) When you're in Elementary OS, open the terminal and type: Code (Text): sudo apt-get install --reinstall grub-efi-amd64 sudo grub-install 8) You can now reboot and everything works again.