Was mucking about with the iphone SDK and even though I told the organizer not to use my iphone for development it would no longer show up in itunes.
Figured I would simply restore it, no biggy, so put the thing in DFU mode, (turn phone off, hold down lock and home for 10 seconds and then release the lock button holding the home button for 10 more seconds). Itunes picked up my phone in restore mode, but when I tried to restore the iphone it returned Unknown error: 1604. And that was it, my iphone had magically transformed into a brick.
I tried a few more off and on key-press, and I tried to restore it a couple more times – nothing.
Thought maybe the Pwnage tool could help me. I didn’t want it hacked bu a hacked iphone is better than a brick. iTunes couldn’t flash the custom firmware either, but I had a different error number now, 8.
Then I thought to try the restore in SDK organizer. It took a mammoth amount of time – and it worked! Yay my iphone works. Maybe someone can explain better than me what the SDK restore does that itunes doesn’t, but my iphone is working again.