Ubuntu – PC still booting on GNU GRUB even after boot-repair

After reading several other threads and tinkering around – I installed efibootmgr at some point too -, I sorted the problem out by running Boot-Repair a second time (with Secure Boot off though), leaving all default settings, as per first time. The URL generated at the end of the process was http://paste.ubuntu.com/5982069/

Interestingly, I read somewhere that Ubuntu 13.04 is Secure Boot compatible; however, when I turned this feature back on and restarted the machine, I incurred in a ‘validation error’, and the system booted straight to Windows 8. I’ve therefore decided to leave it off for good!

Braiam and Oldfred, thank you both for your input and suggestions, much appreciated.

I can get a Grub boot interface by typing:

set root=(hd0,5) 
set prefix=(hd0,5)/boot/grub 
insmod normal 
normal

And I can then boot into either Windows 8 or Ubuntu. But I really don't want to type that every time I reboot.

That was pretty far already. In your UEFI setup you would have just needed to put that into a grub.cfg next to /EFI/ubuntustudio/grubx64.efi.

This is what the configuration file looks like that reads the actual grub.cfg containing all the kernels:

search.fs_uuid $paste_uuid_here root hd0,gpt2
set prefix=($root)'/boot/grub'
configfile $prefix/grub.cfg