Dev team already warned don’t upgrade to 3.0 wait for Next version of pwn.The Dev-Team warns that upgrading to 3.0 with Yellowsn0w installed will cause people to lose Yellowsn0w and will be unable to get it back. Upgrading to 3.0 also upgrades to Modem Firmware 04.20.01 which is not down gradable. iPhone OS 3.0 Leaked on bay of pirates drives you crazy. Don’t download and try to upgrade to 3.0 hold your horses till june. But many of iPhone lovers can’t hold thereselve to update iPhone to 3.0 accidently or in a hurry & loose there jailbreaking.Remember you have downloaded a Dev release means after the installation you might not be able to sync unless you have dev account. Dev account costs you 99$ from Apple Developer Connection.
For the people who wants to downgrade from 3.0 to previous 2.2 or 2.1 use the following steps.
Connect your iPhone to your Mac or PC and select your iPhone from the list of devices in iTunes. If iTunes does not detect your iPhone then you will need to put it in DFU (Device Firmware Upgrade) mode.
You can follow these steps to put your iPhone in DFU mode (this is required only if iTunes does not recognize your iPhone):
- Connect your iPhone to your computer.
- Turn iPhone off.
- Hold power and home together for 10 seconds (exactly).
- Release power but keep holding home until the computers beeps (observed on a PC) as a USB device is recognized.
- A few seconds later iTunes should detect your iPhone.
Browse the Summary Tab, For Mac user Hold down Option and press the “Restore” button. For Windows user hold down Shift and press the Restore button. Now you will be able to browse the folder where you have the iPhone firmware.Select the firmware & hit the restore button and cross your fingers for 5 minutes.
If you get error message like 1011, 1013, 1015, just ignore them(Actually the firmware 2.2 is already successfully installed). Fire Quickpwn 2.2.1 and jailbreak your iPhone use this guide
But if you encountered with error message like 1601, 1602, 1600 or anything else then try putting the iPhone into DFU mode and try again.
If you have an Unlocked iPhone then use pwnage tool to make a custom firmware then enter DFU and restore / downgrade to 2.2.1 if not works in first time done it again n again.