개발이야기

Think you’ve made a mistake by upgrading your iPhone or iPod touch to the latest and greatest iPhone OS beta? iPhone OS 4.0 can be a little buggy and may not even work nicely with some applications, but that didn’t stop some from making the leap. Apple intended for this beta version of the iPhone OS to be strictly for developers and it shows. We're going to show you how to return your device back to OS 3.1.3 far away from those beta bugs.

We suggest reading this how-to in its entirety before proceeding with this process. We successfully downgraded our device from 4.0 to 3.1.2 on multiple iPhone 3GS models, but haven’t tried this process on an iPhone 3G or iPod touch.

Disclaimer: Your mileage may vary, so proceed at your own risk. Mac|Life takes no responsibility if you brick your device.

Difficulty Level: Medium

What You Need:
- An iPhone Running OS 4.0
- A Mac
- iRecovery v. 1.3 for Mac
- Libusb Library


Step 1 - Download iRecovery and Libusb
You’ll need two pieces of software in order to downgrade your device from OS 4.0 back to OS 3.1.3. You can download iRecovery by clicking here (direct-download link). You can download Libusb by clicking here (direct-download link).

You can install Libusb by unzipping and running the installer. Unzip and place the iRecovery script on your Desktop.

Step 2 - Sync Your iPhone
The first part of any OS restore should be to backup and sync your iPhone data. Connect your device to iTunes and click the lovely Sync button. Depending on how many changes you have, this could take a while so get a snack and watch the status bar climb to the finish line.

iPhone OS 4.0 doesn’t allow you to backup your device, so anything that’s not synced over to iTunes will be lost.

Step 3 - Start The Restore
Press alt/option and click the Restore button in iTunes. This will bring up a dialog that will allow you to manually select your iPhone OS firmware. Navigate to User/Library/iTunes/iPhone Software Updates/ and select “iPhone2,1_3.1.3_7E18_Restore.ipsw”. Click Choose and the OS restore process will begin.

If you don’t have this version of the iPhone OS software, then you’ll need to download it by clicking your version below. Then repeat this process by navigating to the download location and selecting it. Click Choose and the OS restore process will begin.

Download iPhone OS 3.1.3 for iPhone 3G

Download iPhone OS 3.1.3 for iPhone 3GS

Your device will most likely show the error "1015" when it is restoring the firmware. Ignore this error as we will take care of it in the next step.

Step 4 - Use iRecovery to complete restore
Now we’re going to use iRecovery to complete the restore process and get around the firmware upgrade problem that we encountered in the previous step.

To do this, launch Terminal (Applications/Utilities) and type in the following commands:

cd Desktop

./iRecovery -s

setenv auto-boot true

saveenv

fsboot

exit

After a few seconds, you can disconnect your iPhone and power it off manually by pressing the power and home buttons simultaneously. Now when you power up your iPhone, you should see the standard connect to iTunes image.

You can now safely connect your iPhone to iTunes.

Step 5 - Restore Your iPhone from a Backup
When you connect your iPhone back to iTunes, you’ll have two options: Set up as a new iPhone or Restore from the backup of. If you’re restoring from a previous backup, select it from the drop down menu and click Continue. If not, select Set up as a new iPhone and continue the on-screen instructions. 

Your device restore will take a few minutes to complete, so you may want to grab a snack and watch the status bar for entertainment (or not, your choice).

Step 6 - Relax You’re Back to 3.1.3
You can now breathe a sigh of relief and pat yourself on the back. Your iPhone has now been safely restored back to its previous OS version (3.1.3). If you’re into jailbreaking, you can now re-jailbreak your device following the same process you followed before.

Process via Gadgets DNA

 모르시면 댓글주세요