I have put search-replace folder on ftp. in directory where we have wp-admin,wp-content,wp-includes directories...
So after uploading search-replace-folder it looks like this
/search-replace-folder
/wp-admin
/wp-content
/wp-includes
/so on
Then I tried to open
http://example.com/search-replace-folder
http://example.com/search-replace-folder/index.php
But Getting same 500 error...
One more thing I have noticed:
If I put wrong database credentials in wp-config.php file then also I am getting same 500 error message.