Double check in cydia first to make sure it says at the top that they have SHSH blobs for 3.1.3 for your device. Quick question why not move on to 4.0?
My understanding was that there's no jailbreak for the current version of 4.0 that's out there -- and I've also heard (perhaps mistakenly) that you lose the ability to unlock once you upgrade to 4.0, and that you can never get that abiltiy back. I've heard that hurts the resale value on a 3GS considerably.
Double check in cydia first to make sure it says at the top that they have SHSH blobs for 3.1.3 for your device. Quick question why not move on to 4.0?
Incorrect on ALL counts.
To OP, do you have old or new bottom (tethered)? If old, your should be pwned. Thus, you can upgrade by creating / finding a custom 3.1.3 firmware to restore with. Just to be safe, make sure you have hashes saved so you can still restore to JB firmware if something goes wrong. You can find out by main window in Cydia or using tinyumbrella.
The devteam blog specifically states there is no jailbreak for 4.0.2. That's the version I'd be upgrading to through iTunes, correct?
The bolded parts are the ones I don't understand.![]()
When your reboot your phone, does it startup normally (old bootrom) or does it get stuck at Apple USB cable image & you must run blackrain to continue (new bottom = tethered)? If first, means your phone is pwned and JB. Pwned phones can accept / run unsign code = custom firmware from pwnagetool and snowbreeze. And, as long as you stay pwned = upgrade only using custom firmware, you can pretty much install any firmware without worry about SHSH hashes.
SHSH hashes are what Apple uses to prevent 3GS and IP4 from installing firmware they don't want. Thus, right now, Apple only allow you to install 4.0.2 and without hashes saved from previous firmware, you won't be able to install them.
I would suggest you do some major research before trying to update your firmware or we will be very sorry you did.