Change name of child theme?

Hello,
I have a child theme which I’ve heavily modified. It’s called Child of Openstrap2, which is a bit of a lousy name for a theme. I’d like to change it, and I’ve tried various methods of doing so, but each tim eI change it, my site gets screwed up – it displays the default “hello world! We are a design agency….” nonsense, as well as some of my proper content.

I’ve tried duplicating the child theme’s folder, renaming it, and changing the “Theme Name:” in the style.css. I also tried this method (tweaking the values in phpMyAdmin), with the same results.

Any suggestions, please?

Thanks,
Paul