Answer to "iPhone could not be restored unknown error 1"I also had the same error when trying to restore my iPhone 4S. I tried all the different suggestions on this forum but it did not work. In the end what worked for me was to put my iPhone in the oven at 100C for 2 hrs. This softens the hardware so that the ipsw iOS is able to update the base 1 chip. My friend also had the same problem on his iPhone 5C. He also tried putting his iPhone in the oven and it worked!