yep, looks like the update borked your site. Upgrading to the latest 3.8.10 should sort in for you but I have not messed with 3 in years so not much I can offer to help you with it. Plenty of vb3 users here and I bet it's been covered here somewhere already..
found it I think..
http://www.vbulletin.com/forum/forum...ite-won-t-load
Code:
includes/config.php
Find:
$config['Database']['dbtype'] = 'mysql';
Replace:
$config['Database']['dbtype'] = 'mysqli';
Lynne beat me to it..