Based on your description, your problem is that you're generating the wrong kind of security exception.
If you have enabled the Administrator IP Whitelist and put your IP address there OR you have your IP address in the "Never block these IPs" option in the Configure WAF page you cannot raise security exceptions. You are allowed to do anything.
Trying to login into the admin login page without the secret admin word always sends you to the home page WITHOUT showing a message that you're an attacker. This is on purpose and documented. The idea is to not give away the fact that you are monitoring your site against brute force attacks. You want the attacker to retry the attack enough times to get auto-banned.
Or maybe you didn't copy the correct file? You need to copy components/com_admintools/views/blocks/default.php to templates/YOUR_TEMPLATE/html/com_admintools/blocks/default.php Please pay attention that there is no "/views/" between com_admintools and blocks in the second path. I know, sounds strange, that's how Joomla! template overrides work. Sometimes I fall for it even to this day if I'm absent-mindedly trying to do an override. It's easy to get it wrong. Typically it's the result of me thinking "oh, I'll just drag'n'drop this into here".
Nicholas K. Dionysopoulos
Lead Developer and Director
🇬🇷Greek: native 🇬🇧English: excellent 🇫🇷French: basic • 🕐 My time zone is Europe / Athens
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