Iboot is the boot loader on iOS devices, and when you perform a system recovery or upgrade in recovery mode, Iboot detects the firmware version you are upgrading to make sure that the firmware version you are upgrading is newer than the firmware version of the current system (the version number is higher). If the firmware version to be upgraded is lower than the firmware version currently installed on the system, Iboot will prevent firmware recovery.
Therefore, to downgrade the firmware, you must switch the device to DFU mode. This means that if you need to restore the current firmware version, just switch the device to recovery mode, itunes will take over the next recovery, and if you need to downgrade the firmware, you need to go into DFU mode.
For example, you can't downgrade your firmware from 7.04 to 7.02 without entering the DFU mode, but now that Apple is officially releasing the new firmware, the front firmware will soon turn off the validation. Of course, firmware shutdown verifies that the firmware is not activated in any way, nor is DFU.
may be more difficult to understand, please read patiently ~
1.DFU mode: DFU's full name is development firmwareupgrade, the actual meaning is the iphone firmware forced lifting level mode.
2. Recovery mode: The recovery mode is the on-screen display of itunes and data line graphs
3. The difference: The two biggest differences are that the DFU mode does not start the Mac OS system, and itunes cannot determine if the iphone's recovery process is interrupted because the system is not started and the related services cannot be enabled. The iphone is said to be more thoroughly restored in DFU mode.
Before brushing the machine preparation work:
1. Fill the phone charge to 100%, and then charge for a few minutes. Can solve the problem of partial battery display error.
1. Mobile phone into the DFU mode: The power-on state, with the data cable to connect with the computer well. Hold down the shutdown key for 2 seconds, then hold down the shutdown key and the home key for 10 seconds, and then hold down the home key for 15 seconds.
2. Check to see if you entered the DFU mode correctly: In DFU mode, the cell phone is black screen. If this is not successful, take the first step again.
3. After entering the DFU state, itunes test to a restored iphone, you can see a Restore button, you hold down the keyboard Shift key, then the left mouse button click "Restore", a window, find the path to the firmware, and then double-click on your downloaded good firmware, Then itunes automatically recovers, never pull the data cable, don't move your iphone, just wait quietly
A window pops up after 4.iTunes recovery is complete. "Your iphone has been restored, this window will automatically shut down in 10 seconds," Close the window, unplug the data cable, don't use the computer to activate the iphone, and activate the system on the phone.
Brush machine in the process of 3004 errors, do not worry. This is due to an Apple server problem. The solution is to turn off itunes. and then re-enter. May now brush the person more load more, can try again later.
