3GS 3.1 able to upgrade to ios 4.0 and jailbreak?

[needuhelp]

I have a 3gs on 3.1 ob, can i upgrade to 4.0 and jailbreak? Thanks

If yes, should i upgrade to 3.1.2 first then 4.0 or i can just upgrade to 4.0 directly?

 

[dhlizard]

I have a 3gs on 3.1 ob, can i upgrade to 4.0 and jailbreak? Thanks

If yes, should i upgrade to 3.1.2 first then 4.0 or i can just upgrade to 4.0 directly?

Jailbreak the phone on 3.1 (if not already) then if you have old bootrom, Use Pwnage Tool to make a custom restore 4.0 (not 4.0.1) IPSW, use iTunes 9.2 to install it.

 

[thelatinist]

As dhlizard said, be sure not to upgrade to the official 4.0 firmware file. Only upgrade to a custom (pre-jailbroken) one.

 

[needuhelp]

Thx for the quick reply