Ah I just realised this tool:-

if (!defined('DEBUG_AUTOLOAD')) define('DEBUG_AUTOLOAD', false);

Is for admin side only I think, I tried developers toolkit to see if it occurs in includes/ . For 1.58a I had blank admin page for so long so this was useful for that, typical I have it other way round now lol.

Though the only log I got since is starting like below, but it mentions debug so must have been when I was trying debu_autoload:-

PHP Code:
--> PHP Warning: Cannot modify header information - headers already sent by (output started at /home/*********/public_html/********/includes/classes/InitSystem.php:58) in /home/***********/public_html/********/includes/init_includes/init_gzip.php on line 34.