I upgraded to 5.6.0.2 and now I get a fatal error. The last time I made an update, it stopped my site from being editable. But now it's totally offline. What the hell!?

Some help with this would be great, thanks.

Warning: require_once(/home/c99media/public_html/rationale/updates/concrete5.6.0.2/concrete/models/json.php) [function.require-once]: failed to open stream: No such file or directory in /home/c99media/public_html/rationale/updates/concrete5.6.0.2/concrete/core/libraries/loader.php on line 40

Fatal error: require_once() [function.require]: Failed opening required '/home/c99media/public_html/rationale/updates/concrete5.6.0.2/concrete/models/json.php' (include_path='/home/c99media/public_html/rationale/libraries/3rdparty:/home/c99media/public_html/rationale/updates/concrete5.6.0.2/concrete/libraries/3rdparty:.:/usr/local/php52/pear') in /home/c99media/public_html/rationale/updates/concrete5.6.0.2/concrete/core/libraries/loader.php on line 40