environment: iPhone 3GS old br with iOS 6.0 official release. OSX 10.8 / iTunes 10.7 I want to downgrade to 5.1.1. I have shsh saved. I open TinyUmbrella, start the server, and iPhone 3GS is in PWN DFU mode. OPen iTunes, ALT + Click "Restore", select 5.1.1 firmware. After a couple sec, got 1600. How can I fix it? Thank you. Attached are some screenshot.