Upgrade iOS 3.1.3

[dhfernz]

Hi,

I am a newbie to jailbreak. I have an iPhone 3GS. Forecast v1.2 gives the following details about my phone

Baseband: 05.12.01
Bootloader: 6.4
Model: MC137

Jailbreakable?: Yes (with Spirit/JBme)
Unlockable?: Already Unlocked
Tethered?: Maybe - Depends if Refurb
BootRom: 359.3.2

Now, i want to upgrade to iOS 4.0 or later. Question is a) Is it possible b) If yes, how do i do it.

You will need to give me a step by step instruction. Don't want the phone to turn brick!

Many thanks in advance.

 

[Mess]

unless you have the SHSH blobs saved for the firmware versions upto date your only going to be able to install 5.0.1

if your next question is, what are SHSH blobs, your answer is, your only going to be able to install 5.0.1

and you wont need step by step instructions for that as you will just connect it to itunes.