Need help upgrading iphone 3g from 3.1.2. to 4.0

[xa007xa]

iPhone 3g with old bootrom. os 3.1.2 and baseband 4.26.08 jailbroken and unlocked.

Need help to upgrade to 4.0 jailbreak and unlock. have the ios 4.0 ipsw and redsnow downloaded from the guides here. When I run redsnow, it just stays on "downloading jailbreak" screen. Cydia says that SHSH for 4.0, 4.0.1, 4.0.2, and 4.1

I tried to do a restore in itunes to 4.0 and it wouldn't do it. I have my hosts file edited accordingly.

Do I need to upgrade to 4.2 in itunes and then do a downgrade to 4.0? Then jailbreak 4.0?

Thanks

[salander85]

Well, actually, that's not a half-bad idea. So long as you have your Cydia blobs saved, it shouldn't be a problem. What I would do in your situation is run TinyUmbrella, and then try again. Also, forget redsnow. Upgrade to normal 4.0, and THEN jailbreak. Just curious, why 4.0? Why not 4.0.1? Then you can jailbreakme and make life much easier on yourself. Just a suggestion!

[iYeow]

To preserve your baseband you need to restore to custom firmware of 4.1 either created by Pwnage tools 4.1.2 or snowbreeze 2.1. Use Redsn0w 0.9.6b6 to put you into dfu mode and restore to CFW of 4.1
Make sure you have updated your itunes.