Recently I got lots of questions for writing UEFI variables (ALT =), I believe it is because users wants to unlock the capability of your system. And some blogs even mentioned how to do it with RU.
Due to the security reason, recent UEFI system firmware will not allow you to modify sensitive settings (variables). And there is no way to change it unless you can update the SPI by a physical programmer.
Here are what error numbers mean (UEFI spec) after you pressed CTRL-W.
I won't be able to provide you on how to make it working, it is what it is from RU's perspective.