As of yesterday, no official downgrade to 4.0.1 possible anymore. If you didn't save shsh and are on 4.0.2, then you cannot downgrade anymore (only old devices can with redsn0w).

Thanks brother!

I also solved the problem with the unlock of firmware 4.02.

Many thanks!!! :D:D:D

are you insane??? how can you unlock without cydia?

Followed steps from these threads:
http://forum.gsmhosting.com/vbb/f456...-02-a-1078191/
http://forum.gsmhosting.com/vbb/f456...0-1-a-1078190/

So thanks to partapmobile, and MPhoneClinic.

1 - I downloaded TinyUmbrella (google it, you'll find a link)
2- Run TinyUmbrella. Click Advanced Option. Select 3Gs 4.01. Select Cydia. Save SHSH.
3 - Same steps as above but Select 3Gs 4.0.2 (cant be too safe)
4 - Edited Local host to say following: 74.208.105.171 gs.apple.com
5 - Rebooted iPhone into Recovery Mode, chose 4.0.1 IPSW

And voila, it worked.

I know i'm probably not creditable because this is my 4th post, but I had a 3Gs with no SHSH saved ever. Followed these steps and officially downgraded to 4.0.1.

Step 2 will get 4.0.1 shsh from Cydia. That only works if you saved it there before August 19. Doing this now with a new 3GS, or one that was never jailbroken will not work. But yes, for most users your steps will probably work.

So thanks to partapmobile, and MPhoneClinic.

same as me..>> newbie iphone never ever save shsh before....But It WORKED 100%

You better enter to this link around.

yes right another site which promises ............

My iphone 3gs i update from itunes 4.0.2 but in half i got error 28 or something,n now its hang on startup itunes cable,so how can i restore n unlock.

3gs 4.0.2 unlock is possbl by dwngrdng
 

No bro its possible...if u r 3gs is 4.0.2 just put u r phone in dfu mode and restore u r phone with 4.0.1.the go to jailbreakme.com jailbreak it and unlock with redsn0w...Enjoyy

will u plsease let me know which site is that?

Yes. It Posible jailbreak and Unlock 3GS 4.0.2 -------->3GS 4.0.1 without save .shsh before .I did last night 6 hr ago ....:)

No, that's not possible. Without shsh you cannot downgrade a 3GS anymore after Aug 19. I assume you (or a tool) changed your hosts file and shsh backup was on Cydia. Please look into your hosts file: If you find a line with gs.apple.com, you are using Cydia shsh. And in Cydia on the top it reads what shsh versions are backed up. It probably reads 4.0.1 there. Please check and tell this to the other users to not mislead others. Thanks!

Yes..I did and many members did same..:)


8/22/2010 20:33:03.703 Asking CYDIA for SHSH blobs for iPhone3GS 4.0.1 (8A306)...
08/22/2010 20:33:15.109 SHSH SUCCESSFULLY saved! [Click Here to Open]
08/22/2010 20:33:15.125 You have saved your SHSH locally and the request was sent to CYDIA. This means that CYDIA DOES have your SHSH. Do NOT bug semaphore about the Cydia home page showing this version.
08/22/2010 20:33:15.140 Caching shsh files...
08/22/2010 20:33:15.156 Found [1] shsh files to cache...
08/22/2010 20:33:15.218 Cached [1] shsh files
08/22/2010 20:33:19.625 Starting TSS service on port 80
08/22/2010 20:33:19.625 TSS Accepting connections...
08/22/2010 20:33:19.640 TSS Server Started!