Hello, I have installed iOS 5 beta 5 on my iPhone 3GS but wanted do downgrade. Therefore I connected my iPhone to my iMac, threw it into DFU mode and chose to restore. iTunes gave an error after spending a lot of time "Preparing iPhone for restore..". The error was "iPhone could not be restored." followed by the error code 1604. I disconnected the iPhone from the computer and tried again but it was the same. Now I tried downloading the 4.3.5 IPSW and chose to restore to iOS 4 but the same thing happened. I read that it might help try with another computer so I tried plugging the iPhone into my Macbook but it is the same. It gives the same error: 1604. Now I am stuck with an iPhone which won't get past the "Connect to iTunes" screen. Does anyone know how I can make my iPhone useable again - or even better, how I can make it useable AND downgrade to iOS 4.3.5?