As mentioned, if the EEPROM reading/drive locking didn't work, your console should give specific error codes on the screen. That's all XBoxHDM wants that file for by the way - locking the drive.
The original XBoxHDM CD you made won't work, because it doesn't include all the files that are needed for your X-Box to boot a dashboard. The stuff obcd got you to do with the "ShadowC_off.bin" file revealed those files you missed. Those files are not optional, hence the reason your softmod installer hid them in the first place - so they didn't get deleted by accident.
Putting just the MS Dash on C should "work" regardless as to which console it comes from, but it's a bit pointless... You should be able to boot games regardless as to what's on C, and it won't help you fix this any more then XBoxHDM will.
Assuming you haven't already got it on the drive (and unless you deleted it from your original drive before copying the contents of E to the new one, you should do... You did copy across everything on E, right?), XBoxHDM will allow you to add the autoinstaller savegame so you can re-do the SplinterCell exploit. Going by everything you've mentioned so far, this would probably be your easiest path at this point.
Oh, one other thing. If you create a partition larger then 256gb, you need to format it with XBPartitioner (check X-Bins for this). Stick that on the top of your to-do list once you get this new drive booting up if you didn't split all that space into smaller allocations. Failure to do so results in the loss of up to nearly all your files.