Comment # 3 on bug 950569 from Neil Rickert

>So there is nothing but a blank screen? That's bad...

Right.  Sometimes there's a cursor at the top left, if I remember correctly.

>Did you use shim.efi from openSUSE 13.2 DVD or the updated one?

The updated one.  This was from 13.2 installed in a different partition on the
same computer.

To be more precise, I used "shim.efi", "grub.efi" and "MokManager.efi" from
13.2.  I took those to be a matched set.  But I can experiment with just one of
those at a time if that would be useful.

When I first booted after the update, it looked to me as if the firmware was
freezing.  So I powered off, powered on, and hit F2 to get into BIOS settings. 
That's when I tried turning off secure-boot.  When that worked, it suggested a
"shim" problem.  So I experimented booting the DVD iso (on USB) with
secure-boot on and off.  And then I put back the ".efi" files from 13.2 to get
things working.

During my tests, I found that CTRL-ALT-DEL does reboot when the system is
sitting on that blank screen.

I'm not sure how to test what is going on.  I think you would need a debugging
version of "shim.efi" and it would need to be signed by Microsoft to be able to
test with secure-boot -- unless there's a way of chaining a debug version from
a working shim.efi, and have the debug version signed with a MokManager key. 
(I do have my own key installed, though I am not currently using it on this
machine).