Ok... before I go too far, let me just say I know I goofed up.
I was feeling pretty good after jailbreaking and unlocking a 3GS for my wife to use... so I offered to try and help a friend unlock her already jailbroken 3G.
Here's the specifics:
iPhone 3G 16GB
iOS 3.1.3 (7E18)
Unfortunately I had not yet determined the method of jailbreaking that was previously used on the phone. Someone else had jailbroken it, and they believed that unlocking it would be impossible.
For what's its worth, I'm using a Windows 7 (32bit) PC running iTunes 10.4.1.10
My mistake: to start out I did a full reset from within the (iPhone) settings menu.
Everything seemed to go fine until it went to reboot. Now it is stuck in a bootloop. At first the bootloop has just the apple logo, but after a bit several thin colored lines appear across the top of the screen and a loading icon starts up near the bottom of the apple. After a bit the loading icon (and everything else) freezes.
I've read through many forums and everybody just says to put it into DFU mode. However, I have tried this repeatedly (paying very careful attention to the timing... and attempting to do so at different stages of the boot process), and I don't see any response from the phone.
Did I brick my friend's phone? Any suggestions? Eventually I would like to get it unlocked for her... but for now I am happy to just hand it back with a blank working phone if possible.
Thanks a bunch!