星期五, 6月 01, 2012

Tutorial on the failsafe method to restore the current version of IOS


Welcome to the iPadForums.net tutorial on the failsafe method to restore the current version of IOS on your device.

 From time to time our iPads do get messed up and you want to get the device back up and running on the latest firmware so you have a fresh platform to start over. This guide will help you get your device restored with the latest firmware whilst avoiding most of the common iTunes errors along the way.

1. Update iTunes to the latest version
 If you are going to install the current version of IOS reliably, make sure you are running the latest version of iTunes. Use the "Check for updates..." menu item in iTunes.

 To restore 5.x IOS you must be on at least iTunes 10.5 or newer...

2. Fix Hosts File
 Lots of iPad owners mess with their hosts file but don't really understand the changes that have been made or why they made them. Usually it is to allow an older firmware to be installed by using SHSH Blobs from Cydia. Having a hosts file which is pointing towards Cydia and not Apple is probably the number one cause of issues when trying to restore a device. Normally, this gives an iTunes Error 3194. To make sure your hosts file is pointing back to Apple, follow this process:
Download the latest version of TinyUmbrella from here - The Firmware Umbrella - TinyUmbrella
Once downloaded, start the TU program
Switch to the "Advanced" tab
UNTICK the option which says "Set Hosts to Cydia on Exit"
Close TinyUmbrella - We will not use this application again during this process, so make sure it is closed.

 Alternatively, if you know what the "hosts" file is and how to edit it manually, remove ALL references to gs.apple.com from the file and save it.
On Windows the hosts file can be found in: C:\Windows\System32\drivers\etc\hosts
On OSX the hosts file lives in /private/etc/hosts

3. Download the IOS5 firmware to your desktop
iTunes is not very forgiving when it comes to unreliable internet connections or times when the download servers are being put under a lot of strain, e.g. when a new firmware is released. Therefore, it is usually best to download the firmware file directly to your desktop and then direct iTunes to use it.

 Download the latest version of IOS for your device from our sticky here - Official Apple IOS Firmware Download Links for iPad

NOTE: - This tutorial does not cover installing an old version of IOS on your device. You can only use this guide to install a version of IOS on your device which Apple is currently signing. DO NOT BE TEMPTED TO PICK AN OLDER VERSION WHICH YOU KNOW IS NO LONGER BEING SIGNED! It will not work using this method.
 If you are using Windows and Internet Explorer, make sure you rename the file back to have an extension of IPSW if it gets renamed with ZIP. This is a fault of Windows and IE, and nothing to do with Apple! You could also consider using a better browser such as Chrome or Firefox to avoid this issue altogether...

4. Put your device into DFU mode
 Restoring a device by just connecting it to iTunes and pressing restore will only work if the iPad is working properly. Invariably, and especially if you are looking at this post, something has gone wrong before you got here, so it is unlikely that a normal restore will work. In order to get the restore to complete normally, you MUST put your device into DFU mode.

 In order to put your device into DFU mode, with the iPad connected to your computer and turned on, you must press the "home" and "power" buttons together for EXACTLY 10 seconds at which point you must release "power" but continue to hold "home". After about 15 seconds, the device will enter DFU mode.

 Once your device is in DFU mode the screen should be blank. If anything else is showing on the screen, such as the "connect to iTunes" logo, you got it wrong. You must get the device into DFU mode successfully. Try again

 If you need more help with DFU mode, see our guide here - DFU Mode for Dummies

5. Temporarily Disable 3rd Party Tools
 Sometimes, 3rd party apps such as firewalls, anti-viruns, and anti-malware software can interfere with the restore process, particularly on Windows. If you are having trouble, it's best to temporarily disable all these on your PC whilst you carry out the restore.

6. Manually restore in iTunes
 Finally, you are ready to restore your device using the firmware you downloaded in Step 2. Make sure it has completed the download of course!

 Open iTunes and it should report that it has discovered a device in recovery mode and must restore it. Good! That's exactly what we want. Click the OK button to dismiss the dialogue box.

 Now you must Shift-Restore (Windows) or Option-Restore (OSX) to select the firmware you downloaded. This means you must hold down the shift key (on Windows) or the option key (on OSX) on your keyboard whilst clicking the "Restore" button in iTunes with your mouse. If you do this correctly, an Explorer or Finder window will pop up and allow you to navigate to the firmware file you downloaded in Step 2. Find the file and choose it for the restore.

Done! iTunes should now restore your firmware file on your iPad without any errors.

 If you run into problems make sure you followed all the steps correctly and also check you are not connecting via a USB Hub. Always connect directly to your PC. Try a different USB port and if possible a different cable, particularly if you are not using the original cable.
 If it still fails after this, post details of the error message and we'll see if we can help.