How to Downgrade Your iPhone 3GS, 3G Baseband for Unlock (Windows)

How to Downgrade Your iPhone 3GS, 3G Baseband for Unlock (Windows)

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Apurva - May 10, 2015 at 4:58am
I am on activation screen of 6.1.6 with baseband 6.15.00. The problem with these steps is that my power button doesn't work and so I created a custom IPSW of 5.1.1 as specified in https://www.iclarified.com/entry/index.php?enid=23009 for putting the phone in DFU mode. Will I be able to use that ipsw to put the phone in DFU mode and downgrade it as specified in this tutorial?