Failed automatic update - KB4489899 and KB4486553

(1) OK. It's a sin that Startup Repair failed when you needed it. One could wish it would either make a repair or declare it couldn't, but not crash. But now that EFI is recognizable (which cured Windows Update), let us see whether Startup Repair will run & what "SrtTrail.txt" looks like. It won't hurt, & the file is small enough to copy/paste.

(2) I don't like a second flip flop of your NVMe drive numbers. I can't think of a reason for it. To my understanding: BIOS is first to put numbers on them, & that is determined by which port they are plugged into. Unless you switch them in the ports or remove one, I'd expect the numbers should stay the same each boot. I'm not sure whether Windows uses the numbers BIOS assigned or discovers them for itself. But I'd think they also would be assigned by the order they are in the ports each boot. Since the numbers can legitimately change by removing, adding or switching drives, I guess it doesn't matter that they change inexplicably too - just remember to do a List Disk in DiskPart to see which is which before doing something destructive like "clean" which would wipe the drive.

The BCD Boot Manager device entry showing HarddiskVolume9 is saying that is the partition that held the boot manager at boot. If EFI is being used, it should point to it. If there were no EFI, I would expect it to point to the Windows partition (C:) which can sometimes double as the system partition. Check it immediately after a boot. If it points to neither of those, maybe BIOS is achieving a boot without a boot manager at all.

Go into BIOS, & report whether it is set to boot to the Windows boot manager (bootmgr) or directly to the SSD.

(3) If 1903 comes in through Windows Update, its unlikely to put EFI where it belongs. But it may give you a recovery partition. OK, wait & see.