Too long since I flew this beast; so forgive me if I've forgotten much. I can't remember the reserve electric motor to release the uplocks. If this didn't work it suggests a multiple failure, but on the same system. It does not sound a good design if the back up of any system has failed and when you need it you find it is not working. Is there no warning of this on the lower screen? Secondly, it seems too complicated to have an electrical back up system. The good old basic cable on the B737 seems perhaps more fail-safe, although someone will have a story to refute that: plus it would be a longer cable.
I do remember the story of a BA B757 on base training duty who could not get the gear down by any means. The solution devised (lucky they had the fuel while the tech gurus devised the solution) was to depressurise the hydraulic system which kept the gear up. Then the back up system could be used and once released aerodynamics + gravity did the rest. Here both primary and back up system failed. I appreciate the back up system is only to release the uplocks. A bad hair day. back to the drawing board Boeing. I'll be interested on the FAA's response.
After this I would expect a detailed update of the FCTM as to how perform this manoeuvre. Sadly, not every airline carries this on board. Strange that the instruction manual is not kept beside the equipment it is relevant to. Where do you keep your car manual? Next will be a glover box in front of F/O.