Plugin uninstalled and still affecting the site

Hi

I know the plugin creator will not read it, but I’m asking it in the hope someone else who is facing the same problem can help me

Basically, my problem started when I became unable to edit my pages (white screen of death shown instead of the edit page), and so when I tried to get rid of this plugin, even following all the steps according to the tutorials in the web (https://journalxtra.com/wordpress/uninstall-w3-total-cache-proper/) it still affects the site, even if there is no code of the plugin, no cache folder, no htaccess interference from it etc.

This SO thread has more details (I asked there too):
http://stackoverflow.com/questions/41210657/w3-total-cache-everything-removed-and-plugin-still-affecting-the-site

Greetings to everyone