After ten minutes, site came back, but now have this in admin:
An automated WordPress update has failed to complete – please attempt the update again now.
I checked the auto update, says I have current version,
You have the latest version of WordPress. Future security updates will be applied automatically.
If you need to re-install version 4.2.3, you can do so here or download the package and re-install manually:
Can’t close the dialogue box.
strange…