Well, OK, I’m not sure what the correct terminology is. It was a phone which shared characteristics with a brick, and took some research and effort to get working again.
I tried the DFU mode thing loads of times - didn’t help.
In the end I downlaoded Blackra1n and used that. It got my phone working again (but it’s still jailbroken, and not restored which is what I wanted to do).
I’m sure it’s perfectly possible, but I’d say that if you don’t know what you’re doing you could be in for some real frustrating experiences.
True, there is always risk of screwing up if you (the general you) don’t know what you’re doing, but in the interest of fighting ignorance and fear - which a lot of people have about bricking their phone with Jailbreak - I want to make clear that Jailbreak does not permanently damage (or “brick”) your phone, and you can always restore back to factory mode.
If you (the specific you) need help with restoring your device, PM me. Otherwise try this:
Upgrade iTunes to the latest version (otherwise you will get an error)
Remove any entries from your hosts file that block Appple servers
Download redsn0w from the link I posted above
Install redsn0w, and select Extras
Run redsn0w, make sure iTunes is not open
Select option to put phone in DFU mode
Follow instructions to put your phone into DFU mode. This takes a few tries, and is just a matter of timing the steps right. If you see the iTunes logo, you are not in DFU mode. In DFU mode your screen should be black (powered on, but all pixels black)
Launch iTunes
Connect your phone, iTunes should recognize your phone in DFU mode. If it does not, you’re not in DFU mode. Repeat above steps
Restore your phone to factory
If you’re on Windows, go to Start/Run and type in “cmd” (without quotes) and then hit Enter. You should see a black and white screen. Type “ping gs.apple.com” (without quotes) and hit Enter. What IP address does it return?