It was working fine with Leap 15.0 and KDE desktop. I updated to 15.1 using a DVD. So it boots, and gets to the
Leap 15.1 boot screen
then the last thing that appears is
loading init ramdisk
before the screen goes blank. I noticed also that the lights on the ethernet port are not lit up.
It is an old system: i7 P55 chipset, so hardly new unsupported hardware.
Only if I select the old kernel 4.12.14lp150 will it boot up to a functioning GUI desktop.
So I guess I must wait for a new kernel to emerge in coming updates?