My site, I was locked out, so I renamed main.php to main-disable.php as per the instructions you provide. Now I'm back in and I've renamed the file main.php again.
I always get the: Your Admin Tools installation is corrupt message stating that main.php is not there (I've checked with FTP it is there). I've also overwritten it with an original version but that did not help.
The run files check button doesn't solve the issue, it just tells it's that file it's concerned about.