4、先按住开机键出现Apple Logo，同时按住开关机键和home键，持续直至logo消失，继续按住约4－5秒放开Power键，并继续保持按住home键直至iTunes检测到一台处于恢复模式的iPhone（成功的话iPhone应该处于黑屏状态）。DFU的全称是Device Firmware Upgrade，即iPhone固件的强制升降级模式。
NOTE To get the latest firmware/software/electronic manuals/support information, visit Agilent Technologies support site (http://.home.agilent), and click Additional Test & Measurement Products > Parametric Test, click Semiconductor Parameter/Device Analyzer Series, and click B1500A Semiconductor De...