Redsn0w gives the message “ This device is already pwned with a bootrom exploit. For the time being, redsnow requires that you manually select the IPSW in the Extras screen in order to specify the current build. This will be fixed in a future release. ” while updating the baseband to 06.15.00

The solution for this is simple.

1)      Download IPSW file for your Iphone from the web.

2)      Open the folder in which redsnow is saved

3)      Right click on redsnow and click on Run as Administrator

4)      Once the redsnow opens click on “Extras”

 

5)      Click “Select IPSW”

 6)      Select the IPSW and click “open”

7)      Click “ok”

8)      Click “Yes”

 

 9)     Click "back"

 

10)      Click "Jailbrea"

 

 11)      Click on Install Ipad baseband and follow the instructions provided by redsn0w