I tried, but it didnt work....

[q2subzero]

I tried every guide i could find here, and pretty much bricked my iphone 3gs.

I had a nicely jail broken (via blackra1n) 3.1.2 OS with the old boot rom and wanted to upgrade to iOS4 while still being jail broken.
-I downloaded the iOS4 file, had it modified.
-Put my iphone in recovery mode
-attached the iphone to the computer, hold shift+recover and selected the modified iOS4 file.

-ERROR 1604.... constantly. i looked it up, was "a usb issue" so I tried all 8 of my usb ports on my desktop. still same error. I even tried doing this on my laptop... same error. >_<'

I tried re-doing the guide several times. Every time still ERROR 1604 when trying to apply the new OS/old OS, and one time i got a 19xx error code. The phone would simply not take this, OR an unmodified iOS4.0 file!

I even tried going back to the stock 3.1.2 software... NOPE.. would not validate with Apple.

I am unhappy to announce I'm running the latest 4.0.2 software on my phone now, b/c that's the ONLY thing that would work! Same USB ports, and it worked!?!

My only hope is someone comes out with a j/b for this soon, stock iphones are 10% as fun as j/b ones.

Is there any way to reset the phone and go back to my 3.1.2 software? I miss my j/b phone!

[eyeRobot]

If you were JB before did you not save your SHSH files? Did you hit "make my life easier" in Cydia? If so, then you can downgrade your firmware and rejailbreak.

If not, then I also saw something on Redmondpie.com this morning about JB 4.0.2 with unofficial pwnagetool. It's worth a try if you are really stuck but maybe wait a while to see if anyone has suceeded before you dive in.

[i.Annie]

Downgrade back to 4.0.1 and activate with official SIM, jailbreak with jailbreakme. As far as I know, 4.0.1 is still being signed so you can downgrade without SHSHs. But be sure after you jailbreak, immediately go to Cydia and select "make my life easier" to back up your 4.0.1 SHSHs before Apple quits signing it. You can also use TinyUmbrella on your comp to back them up.

[q2subzero]

Downgrade back to 4.0.1 and activate with official SIM, jailbreak with jailbreakme. As far as I know, 4.0.1 is still being signed so you can downgrade without SHSHs. But be sure after you jailbreak, immediately go to Cydia and select "make my life easier" to back up your 4.0.1 SHSHs before Apple quits signing it. You can also use TinyUmbrella on your comp to back them up.

I tried goin back 4.0 and 4.0.1 iOS... but i keep getting the same usb error code right after "waiting for your iphone..." just sits there for 5-10 minutes, then error code pops up.

What I dont get, is how the update straight from itunes was able to update the iphone, yet all 10+ of my attempts with other iOS software/force updates came up with the error. any insights on this?

[XFaega]

Have you tried DFU mode then restore?

[i.Annie]

You cant go to 4.0 without SHSHs. Only 4.0.1.

Someone with a 3GS i responded to just now got it down to 4.0.1 without a problem, it should work. Try again. Restart your comp and use a diff usb port, then try the shift+restore again.

Like ^ said, put it in DFU first.

[q2subzero]

Have you tried DFU mode then restore?

DFU mode?

nope. what do i gotta do?

Ok, i tried going into DFU mode, it's not working.

How To: Enter DFU Restore Mode - ModMyi - Wiki

After i let go of the power/sleep button and a few seconds later... itunes says the iphone is in recovery mode, and there's a blank display on the 3gs.

any help?

wohoo! 4.0.1 is being installed as i'm typing this!!!!!!!!!!!!

hopefully i'll have my iphone j/b again shortly. thanks for the tip to going with 4.0.1 software. seems like its installing w/out an issue.

[Captain Skyhawk]

You can JB 4.0.2 mad easy. Just use redsn0w and point to the ios4.0 image. Thats what I did worked for me.

[jkmonkey]

You can JB 4.0.2 mad easy. Just use redsn0w and point to the ios4.0 image. Thats what I did worked for me.

Redsn0w is only for 3G phones not 3GS.

[q2subzero]

My phone is happily jailbroken again... 4.0.1 software via jailbreakme.com

i'm very happy to have cydia again as well as rock and many more.

thanks again for the tip of trying 4.0.1.... i thought i was going to be stuck at 4.0.2 for a long time.