How to Enter DFU Mode on iPhone 4 and Fix Boot Loops
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ronqu • December 15, 2012 at 9:08pm
I am having trouble with my iPhone 4 running iOS 6. After installing some Cydia themes, the device crashed and is now stuck in a boot loop, restarting every few seconds. I am unable to enter DFU mode to perform a tethered boot. Are there any tips or steps to fix this issue and successfully enter DFU mode?
Answers
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iClarified • January 12, 2026 at 4:12am
To put your iPhone 4 into DFU mode, connect it to your computer and launch iTunes. Hold down both the Home button and the Power button for exactly 10 seconds. Release the Power button but continue holding the Home button for another 15 seconds. iTunes should notify you that it has detected an iPhone in recovery mode, though the screen will remain black. If you are stuck in a boot loop because of a Cydia theme, you can also try entering No Substrate Mode. To do this, hold the Volume Up button while the device is booting. This will allow the phone to boot without loading tweaks, so you can open Cydia and uninstall the problematic theme.
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PunkoHead • December 17, 2012 at 12:58am
To enter No Substrate Mode on an iPhone 4, hold the Volume Up button while the device is booting. This will disable any jailbreak tweaks that might be causing a crash, allowing you to access Cydia and fix the issue.
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ishwor • December 17, 2012 at 6:45pm
If you can get the device to stay on, go into Cydia and remove the specific theme or the repository you recently added. Often, poorly optimized themes or incompatible tweaks from third-party repositories can cause persistent reboot loops.