After boot-repair failed to install (both with secure boot disabled and enabled), I decided to try running grub-install manually using the following command.
sudo grub-install --root-directory=/mnt/root/ --efi-directory=/boot --uefi-secure-boot /dev/sda7
/dev/sda7 is the root for the Ubuntu install. however, this prints
Installing for i386-pc platform., and I'm on a 64 bit machine. It fails, saying:
grub-install: warning: File system `ext2' doesn't support embedding. grub-install: warning: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged. grub install: error: will not proceed with blocklists.
I tried adding
--target=x86_64-efi, but that prompted
grub-install: error: /usr/lib/grub/x86_64-efi/modinfo.sh doesn't exist. Please specify --target or --directory.
ls showed that, indeed, this file didn't exist.
ubuntu@ubuntu:/$ ls /usr/lib/grub grub-mkconfig_lib i386-pc
I don't really know what to do now. I'm currently running Ubuntu 14.04 on a live USB. The machine is a Toshiba Sattellite P55t with an i5.