Jailbreak 3GS from v3.1.3

[m0m0]

Have a JB & unlocked 3GS with v3.1.3. Was holding out on the v4 upgrade because didn't have time or energy to do. And of course now, a lot of apps out there require v4 iOS...

And since I waited too long, itunes now offers v4.3 upgrade.

What is best method to get to v.4.2.1 or lower?

Thanks for the help!

BTW ...

BB 5.13.04
Have saved SHSH blobs.

I don't really care about conserving unlock right now, dont need it. Am on ATT.

 

[Ipheuria]

The best method is to use a custom ipsw for 4.2 made with pwnage tool. I believe sn0wbreeze is the Windows equivalent but I've never used that. You can go to iClarified - Apple News and Tutorials look in Tutorials -> iPhone -> Jailbreak and look up the method you want to use. I'm not sure if you will get an error when you try to reload with the 4.2 since Apple stopped signing I thought pwnage tool got around that I never had any problems when I've done my phones. You have your SHSH blobs saved anyway so look up the post about editing your hosts file to point to Saurik's server and this should fix that problem.

 

[myzhi]

I suggest you still save your baseband for resale value or you might need it in the future.

Instructions:

1) Create (Pwnagetool) or find (google) a custom 4.2.1 firmware file (non activated and keeps the baseband)
2) Download and run Tinyumbrella. Make sure your iPhone is detected and click on "Save my SHSH...". Afterward, make sure 4.2.1 SHSH was saved.
3) In Tinyumbrella, select "TSS Server...".
4) Loadup iTunes and restore with the 4.2.1 custom firmware file (from step #1).
5) if you get an error, use Tinybrella's "Kick out of recovery".
6) Once you phone boots up, it's JB and ready to go.