Upgrading 3GS from 3.1.2 to 4.0.1

[Jaddy06]

I have an iphone 3gs ios 3.1.2 jailbroken using blackrain. I want to upgrade it to ios 4.0.1 and jalibreak it using jailbreakme.com. I have shsh saved for 3.1.3, 4.0 and 4.0.1. I need step by step guide please

[iYeow]

Download the 3GS, 4.0.1 ipsw from here :
iClarified - iPhone - Where To Download iPhone Firmware Files From
PC : Run Notepad as Admin and open up to your hosts file .
CWindows\System32\Drivers\etc\hosts and add this line to the very bottom : 74.208.10.249 gs.apple.com
save it and reboot your pc
Now having your iphone pluged in, Do the Shift key + Restore ( Itunes)
and browse to 4.0.1 which you have downloaded.
Let it restore, it should restore if you have shsh blogs with Cydia.
Once restored , jailbreak with jailbreakme.com

[Jaddy06]

Thanks for your response. One more thing please. When i open that hosts file it has local host at the very bottom which is without "#" sign.Does it matter? And will i be able to unlock my iphone after jailbreaking it?

[iYeow]

Can you temporarily check all with # infront and just leave the ip address i mentioned above so as to avoid conflict.
Yes, you can still unlock with Ultrasn0w at 4.0.1.

[Jaddy06]

when i restored my iphone. its in recovery mode. what should i do now?

[iYeow]

If you are getting error 1015, use kick out of recovery from tiny umbrella. You should be in emergency screen

[Jaddy06]

i am not getting any error number but yes i am in emergency screen and also in recovery mode. how can i kick out of recovery using tiny umbrella?

[iYeow]

If you see a slider, you are in emergency. You need an official sim to trigger into springboard .
I thought you already knew this part called activation

[Jaddy06]

yes i see the slider but i cannot arrange to have an official sim so please tell me some other way to put it out of recovery

[eyeRobot]

Do you have new or old bootrom?

How to Check iPhone 3GS New Bootrom / Old Bootrom (iBoot) Version | Redmond Pie

[Jaddy06]

when i open that device instance id it gives me the following details

USB\VID_05AC&PID_1227\5&28E271E&0&3.

ok i managed to check it on my laptop and i have old bootrom. What can be done now? And my phone is in dfu mode now

Finally i arranged the official sim and my phone is working fine on ios 4.0.1. Thanks for the help