IPHONE 4 ONLY
I've also seen a TON of questions about how to update from 4.0.x to 4.1 WITHOUT updating your baseband. I'll give you a quick rundown of how to do it.
Get the latest TinyUmbrella (4.1.3)
READ THE README TinyUmbrella README NOW Yes. You Read it.
Run TinyUmbrella.
Start TSS Server
Open iTunes
Restore 4.1 (NOT UPDATE) Yes this requires you to download 4.1 Here
Let iTunes error with 1004 error (baseband update failed - we want this )
Kick Device Out of Recovery
\o/ -- You are now on 4.1 with 1.59.00 baseband!
Also, here is another good tutorial with more details.
I have heard a few folks voice concerns about how they can downgrade their 2.x baseband to 1.59.00 on iPhone4. Here are the basic steps:
Close TinyUmbrella (if open)
Close iTunes (if open)
Remove ALL lines in your hosts file that contain gs.apple.com
Windows: Start -> cmd -> ipconfig /flushdns
Mac: Terminal -> dscacheutil -flushcache
Start iTunes
Restore (NOT UPDATE) Stock 4.0.2 iPhone 4 - 4.0.2 Download
Note that this will only work while Apple is signing 4.0.2 SHSH requests. This is due to the way Apple now updates/restores Baseband Firmware for the iPhone 4 different from the way it did to prior devices. Lucky us...
