As far as re-direct ... just after upgrading/updating the Moodle code files, Moodle would 'throw' the admin user into the screens for upgrading. But it wouldn't switch to https by itself. Since you've been into editing the config.php file, check to see if the $CFG->wwwroot variable has https rather than http.
Also, in addition to commenting out the line you added to config.php, clear the browser cache/cookies for the site before attempting to re-access.
What file isn't found?
Could be an in-complete replacement of Moodle code IF you are using FTP to do that.
Might help to know what version of Moodle and exactly how you attempted the upgrade.
'spirit of sharing', Ken