change from zip to ipsw

[philfromdover]

hi
i know this may seem a silly question to you all but please can someone explain to me how i change a zip file to ipsw.
the way i do it is . i download the zip file and then once its downloaded i just delete i zip and replace it with ipsw then extract it. is that correct

[Simon]

Yes thats right as long as you have show extensions for known file types enabled. Does the icon change when you do it?

[philfromdover]

hi
no nothing changes
can you explain how i change the file please

[Simon]

See here for how to: File Extensions - Hide or Show - Windows 7 Forums

[iYeow]

hi
no nothing changes
can you explain how i change the file please

My friend, when you run redsn0w , you chose the wrong stock firmware, it should be a stock 3gs 4.2.1 but you chose stock iphone 4 4.2.1, that is why your Limera1n does not work.
Once you browse to stock 4.2.1, it will do the exploit and check only dfu mode. Once dfu is done, run itunes : now shift + restore to 3gs custom firmware of 4.2.1.
Most of guys that PM me says it works like a charm

[philfromdover]

I would just like to say a very big thank you for all your help iyeow. Before i got your help i went to my local mobile repair shop and they looked at my phone and told me that i had burn the phone out as they couldnt do it. So once again a very very big thank you.you are a genious

[michaeljacobs]

Easiest thing to do is download the firmware with firefox becuase then you would not need to alter the file extension as firefox will download the file as an ipsw ready for you to use.