If you get a white page turning on the vb3 integration you need to edit config-int.php and make sure the path to your vb
forum is correct on the $vbpath line
I would suggest you post a link so we see where your at so we can tell you what you might need to do and as always you should have backups before you start an upgrade. Your files are all still 4.85 so you need to actually upgrade the files and run through the upgrade once if you have not done so. You never run the 485 upgrade more than once.