@et al:
Oopsie . . . something went "sideways" on me . . . seems like my fear of "the black screen" has pulled me into the dark vortex of . . . blackness . . . . Booted Siduction this morning and that went well, again did not revive from suspend with keystroke or mouse, but, pushing power button did bring the Siduction log in screen . . . . Did my usual checks of various items online . . . somewhere in there was a Plasma "updates available" symbol in the toolbar . . . I was doing other stuff so I just clicked "install" . . . went to eat breakfast . . . came back and the "progress bars" on the two updates showed something like "34%" . . . but the spinning arrows weren't spinning?? I refreshed the page and it showed "no updates, system up to date" . . . continued on with using Siduction . . . . Then I wanted to restart back into OSX and I held the alt/option key down to get the OSX boot manager window . . . nothing, went to GRUB, which the grub window loaded, but couldn't tab down through the menu . . . the top item is "Leap 15.1" . . . it says it's loading, but, screen goes . . . black" . . . . Display power button shows "blue" like it is receiving video, but nothing appears . . . .
I had this "frozen Grub" issue last week, as I was going through my various linux installs to update them, but it "solved itself" when I shut the computer down. So far on a number of reboots Grub is the only thing that loads, it's "frozen" to the top choice, which doesn't boot.
I pulled the two HDs that have "multi-boot" partitions, i.e., a number of systems in the EFI partition, and I just left in the SSD that has only OSX 10.14.5 installed . . . computer boots up fine, video works, had the side door off, and the **old** Nvidia card has a spinning "fan" . . . . With all the HDs in . . . problem is back. Ideas??