07-26-2015 06:03 AM
Good news. I've managed to resolve the problem. Just in case anyone else has the same issue.
I reset the bios to factory settings, and disabled the secure boot entirely and it updated! You could try with just the latter first, else do a full reset.
If you reset you might find that the system won't boot from the hard/ss drive. You have to switch UEFI to "Both". At least that is what I found.