Unmounted HDD and the latest Security update

Question

Yesterday I installed the latest security/Java update and it crashed my system, just like it has done to quite a few other people: http://discussions.apple.com/thread.jspa?messageID=9053491#9053491
In trying to reinstall OS X, I ran across what I guess is the second installation disc error, where after the first disc is installed and the system reboots, it never finishes booting nor does it ask for the second disc.
I thought my problem might be a HDD error, so I ran the installation disc and did the Disk Utility. I asked it to repair the disc if needed. It could not complete the repair because of an "Invalid sibling link." And this is where things went really bad.
Foolishly, I searched the internet for "invalid siblining link" and found this site: http://www.macosxhints.com/article.php?story=20070204093925888
Which suggests that to fix this error you need to unmount your HDD and run fsck_hfs -r in the Terminal.
Why would I be so stupid as to follow this advice and unmount my HDD with little-to-no understanding of what unmounting does or of Terminal commands? Why would I not bother to read the comments following that post which decry the dangers of unmounting? The only excuse I can think of was that I was delirious after nearly 8 hours of trying to salvage my iMac from the Java/Security update. Needless to say, I successfully unmounted my HDD but did not successfully run the fsck test. Leaving me without a HDD and unable to install OS X.
At this point, I'm planning on taking to the Genius Bar in Austin over the weekend, hoping that they can salvage my new machine (less than a year old!) from the mess I/Apple made. Any one have any suggestions on remounting a HDD or any advice in general?

Answer 1

A wiser head may step in on this as regards to the mounting issue, but I am not currently under the impression that that is what is wrong. I think that command only applies when you are running the computer and once you turn off the computer and turn it on again the drive should appear in Disk Utility. In fact, if the drive were wiped clean your Disk Utility should see it. Yes, if you unmount it to run fsk, you then need to mount it to get it to show under that session, but if you turned off the computer or restarted it then all would be reset.
So, if you turn off your computer, boot from your install Disk and start up Disk Utility, does the drive show up at all? If so you're off the a start. If not then it is suggesting serious problems (terminal?) with the drive.