I just softmodded a box that I got from a thrift store the other day with the Splinter Cell exploit, turns out it had been softmodded before and gave me some problems because there were modded files on the hard drive and Softmod Installer Deluxe didn't want to make a backup because of it and without a MS Dash backup it wont run the installer. However, since I was still able to load the exploit, I could connect via FTP and fix things so I could get it softmodded correctly. I would give it a try if you really feel stuck. Using that should be able to fix your problem, or at least get you to a point where it's easier to fix the problem.
Also when you get it sorted out, if you have an Xbox that can be TSOP flashed - do it. I had 3 softmodded boxes for the longest time and then I finally decided to flash one of them. Best thing I ever did, you can just plug in a new hard drive and rebuild it with Auto Installer Deluxe DVD. No hot swapping or getting a drive that can be locked or anything, it just works. I've since flashed all of mine that support it. If you're worried about soldering, just buy some conductive paint online and one of the really small paint brushes for model building. You can basically put two paint blots on the board and that's all you have to do.