How does one actually utilize the blobs to downgrade or even upgrade?

[dacapo]

Once the spirit gets released, I assume that Apple will eventually/quickly? provide a firmware upgrade.

For 3GS users on 3.1.3, I assume that they will be able to use spirit to jailbreak. And as long as they save their blobs on cydia, they will be able to downgrade back to 3.1.3 even if Apple releases a firmware upgrade and users "accidentally" update their firmware.

For 3GS users on 3.1.2 like myself, should I upgrade to 3.1.3 sooner to take advantage of spirit? (In other words, let's hypothetically assume that Apple stops signing 3.1.3 in the next 2 or 3 days. Does that mean I will not be able to upgrade to 3.1.3 unless I have my blobs saved on cydia? Or, can I upgrade to 3.1.3 even after Apple has stopped signing 3.1.3?)

And, for upgrading or downgrading the firmware, what are the actual steps I need to take?

[I've been happily jailbroken thanks to the great help here, but with the impending spirit release, I find that I'm a complete noob again! ]

 

[dhlizard]

Once the spirit gets released, I assume that Apple will eventually/quickly? provide a firmware upgrade.

For 3GS users on 3.1.3, I assume that they will be able to use spirit to jailbreak. And as long as they save their blobs on cydia, they will be able to downgrade back to 3.1.3 even if Apple releases a firmware upgrade and users "accidentally" update their firmware.

For 3GS users on 3.1.2 like myself, should I upgrade to 3.1.3 sooner to take advantage of spirit? (In other words, let's hypothetically assume that Apple stops signing 3.1.3 in the next 2 or 3 days. Does that mean I will not be able to upgrade to 3.1.3 unless I have my blobs saved on cydia? Or, can I upgrade to 3.1.3 even after Apple has stopped signing 3.1.3?)

And, for upgrading or downgrading the firmware, what are the actual steps I need to take?

[I've been happily jailbroken thanks to the great help here, but with the impending spirit release, I find that I'm a complete noob again! ]

http://www.saurik.com/id/12

 

[dacapo]

http://www.saurik.com/id/12

Is this the section?

Performing the Restore
Now, one would have hoped that the process would be as easy as "restore using the 3.0 IPSW". If only we were that lucky. The first problem is that a downgrade from 3.1 to 3.0 must be initiated in DFU mode.
So, we begin: hold down the lock and menu buttons (some call these the power and home buttons) for 10 seconds, letting go of the lock button but continuing to hold menu until iTunes recognizes the device with the message: "iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes.".
Note that, at this point, your iPhone's screen should be entirely black. Many people confuse "DFU" with "recovery" (and in fact, iTunes itself glosses over this), but they are quite different. If you see anything on your screen, such as the iTunes logo and a sync cable, or a cartoon of Steve Jobs swearing in Cyrillic, you are in recovery mode and need to try again. One can find videos online that may help.
At this point, you should do a "normal" restore to the 3.0 software. When doing this, remember to hold down the option key (on Mac OS X) or the shift key (Windows) while clicking the Restore button in iTunes. Select the firmware (which is probably named iPhone2,1_3.0_7A341_Restore.ipsw), and things should be on their way.

 

[gwynne]

This is a topic that it seems to be difficult to get straight answers on. I'd be interested to know too.

 

[dhlizard]

Here is another one

http://www.hackthatphone.com/3x/local_ecid_shsh_page2.html