[Daniel Thomas]

Apparently the server has crashed or else they are dossing it because its been down for several hours now.

You don't need the /install/ directory once you have upgraded/installed, you should delete it once you have finished with it.

If I remove all the contents from the install folder, then there is nothing for me to reinstall the vbstyles, because once he hacks it, everything is screwed up. You can't login to the admincp or anything, whatsoever. I must use the finalupgrade.php Step 4 to reinstall the vbulletin-style.xml file to get it working again so I can log in.

What version of vBulletin are you using?
Are there any other scripts running on your domain? (that are not part of default vBulletin, e.g. Wordpress or something)

3.6.4
There are no other scripts other than VB in the forums subdomain.

They could just be editing the style directly from the database, although it is a little difficult, it is not impossible. Check the Administration Logs in the vBulletin AdminCP to see if it was edited by another Admin (he may have gained access to their account).

As I stated earlier, I'm the only one who has the permissions to edit styles and I'm also the only administrator who has logged in and he was hacking the forum while I was still on it. he's probably hacked it 6-7 times now.

If you keep restoring old things he will just take it down again.

I have to restore vbulletin-style.xml in order to get the forum working again.

EDIT:
The only other alternative I know of is that he somehow either found a flaw in the coding or else has hacked the server in some way because I found a file called update.php that they kept installing on the server that would overwrite the forum, allowing them to put that message on the board. He probably installed it two or three times and everytime I found it, I chmodded it to disable it and then he would install a new one in a different spot. Once I can get back on the server, I'll let yall see it.