Well, I tried to restore my firmware to 1.1.4 fresh/factory settings. After awhile, I got a message "This iPhone 'Phone' could not be restored. Error 1602". Tried everything from pressing Sleep/Wake + Home button and also the DFU modes. All methods didn't work.

Then I downloaded iLiberty, and press Jump Out of Recovery Mode. It's fine and I can use the iPhone as normal but can't make any calls or texting. Tried to restore back with iTunes and back to the error 1602. What should I do now?