Working on a stubborn 3gs. Every time it restores, it completes successfully, and reboots back to DFU mode. Never see an apple or itunes cable on screen. I see the restore progress bar- then black screen immediately back to DFU mode. I can then even re-jailbreak it with redsn0w but never boots back up - always back to DFU.

Publish your restore log files

http://www.hackint0sh.org/f137/130802.htm

We can't do much without this information.