$:/temp/ServerConnection/http:tiddlywiki.com/library/v5.1.13/index.html
in the system tiddlers, deleted it, and viola!
the chevrons on a green button appear, instead of an empty search box field.
Mark, Greg, Thank you very much.
And now, the plugin hunt begins...
So I learned something here. I tried to access the plugin library before I had acknowledged the Starbucks login screen on a browser. This loaded a system tiddler
which blocked any further attempts to get to the library.
Deleting the system tiddler was all that was needed.