Thanks - turning on debug log in Advanced Settings was enough to get me going. I got a message saying “failed to load the view” and it was enough to spot some case-sensitivity issues in the file names.
Now I have a working dashlet, yay 
I am just starting, but my goal here is to provide an up-front list of links to menu options, with a paragraph for each to document it. This is to guide half-technical users (the guy at the company that is allowed to change settings in the UI) to the relevant menu options and what he can configure in each, instead of getting lost in over-crowded menus.
Thanks for getting me unstuck 