Device Firmware Upgrade (DFU) mode

A mode in which a device’s Boot ROM code waits to be recovered via USB. The screen is black when in DFU mode, but upon connecting to a computer with the Finder or iTunes, the following prompt is presented: “The Finder (or iTunes) has detected an iPhone (or iPad) in Recovery mode. The user must restore this iPhone (or iPad) before it can be used with the Finder (or iTunes).”