How to Jailbreak iOS 4.0 with Sn0wbreeze 1.6.1 on Windows

1* Download iPhone 3G 4.0 Firmware / iPhone 3GS 4.0 Firmware.
2* Download iTunes 9.2
3* Download Sn0wbreeze 1.6.1 for Windows
4* Put everything in one folder and name is “ios4.0”
5* Now Start sn0wbreeze 1.6.1 and click “blue arrow” and select “simple mode” and continue.

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If you select expert mode you will be able to get thru many options include ability to install custom boot/recovery logo etc.

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6* Now browse and select iOS 4.0 ipsw file downloaded in step 1 for your respective device

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7* Sn0wbreeze 1.6.1 will process 4.0 ipsw and will verify select ipsw file

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8* Now click on Blue arrow icon and wait for Sn0wbreeze 1.6.1 to complete processing

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9* Click yes/ no if you want to activate iPhone

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10* Let Sn0wbreeze 1.6.1 to complete rest of its process

11* Sn0wbreeze 1.6.1 will show the message once it has done, now select whether your iPhone 3G is jailbroken or not

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12* Now connect your iphone and enter in Recovery mode after that launch itunes and hold down while clicking the restore button on iTunes

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13* Now let iTunes complete installing iOS 4.0 custom firmware on your iPhone 3G/3GS.
Once your iPhone restarts, the jailbreak process will complete, now enjoy your jailbroken iPhone 3G/3GS 4.0.

Unlock iOS 4.0
Follow our guide to Unlock iOS 4.0 on iPhone 3G/3GS with Ultrasn0w 0.93