Had this issue with a Dell Inspiron 531 with an AMD Athlon 64 X2 4400+ processor. Machine tried to apply the January cumulative update KB4056892
and then failed to reboot, on the second restart it backed out the update. I paused updates twice and then downloaded and manually applied 2018-03 Cumulative Update for Windows 10 Version 1709 for x64-based Systems (KB4089848) from the Microsoft Update Catalog site
Machine rebooted and all seems OK
Thanks, Nigel.
I gave up a couple of weeks ago and let Microsoft fix it, as I'm covered under their Assure Software Support Program.
Jeff