Can't login to any of my sites after activiting Hide Backend

I’ve installed this plugin on several of my websites; and activated Hide Backend. I’ve tried using the secret code with the url found in the .htaccess file — in some cases, I see the login page but upon putting in credentials and hitting Submit, I go to a 404. In other cases, I don’t see the login screen, I just go to a 404 page.

I’ve tried deleting the .htaccess; and also editing it to remove all the WP Security code. Nothing helps; I can’t login to any of my sites.

Can someone please give me some suggestions on what to do? I have looked through all the entries here because it seems that many people are having this problem; but none of the solutions seem to be helping me.

Thanks!

https://www.ads-software.com/extend/plugins/better-wp-security/