So I uploaded Ablaze2 to my themes/ folder, amended _config.php in 'mysite/' to reflect the new theme name...
In my browser I appended ?flush=1 to my main site root, and it just brought me back to the install.php page.
When I saw that something was wrong, I amended _config.php back to use BlackCandy, but every page I went to brought me back to install.php.
I tried to flush the template with ?theme=blackcandy&flush=1.
Still back to install.php.
So effectively my installation was ruined.
So I did a totally clean install of SilverStripe, with a new empty database, and repeated what I had done -
Uploaded the theme, amended the _config file, again same results.
I will try for a 3rd time with another theme.
I have seen this problem raised on this forum but not answered - does anyone know the specific reason this might have happened, or even guess at a principle ? I followed the instructions to the letter and just lost 2 hours trying to fix and duplicate the error. :(