Ok so I bought an iPhone 2g not so long ago and it came with official os 3.0 from apple. But I noticed that it made my iPhone have a shorter battery life. I tried to downgrade to 2.2.1 with iTunes 8.2 (apple tells you to update itunes, or you cannot sync items into your iPhone). I tried going on DFU and it always gave me error 1600... That was so frustrating, and also tried to google a tutorial and did not find even one helping tutorial. I found a solution not so long ago... So follow these instructions on how to downgrade to 2.2.1, how to jailbreak and also unlock.

Downloads

You need to download the iPhone 2G 5h11a restore from here
9 iPod and iPhone Firmware Download )

Then you need to download quickpwn 2.2.5 for windows from here ( http://miphone.ca/iphone-dev/QuickPwn225-2.zip )

Then you need to download iTunes 7.7 from here ( Download iTunes, iTunes 7.7 Download )

You also need to download and extract Bootloaders from here ( FileSend - BOOTLOADERS FOR iPhone 2G [iPhoneArena@youtube].zip )
Installing

1.So now go to control panel > Add or remove programs > remove itunes.

2.Now also go to My documents > My music > iTunes> and erase the iTunes library.itl file.

3.Go and install iTunes 7.7, this is required, you cannot downgrade with itunes 8.2

4.Connect your iPhone, a pop up should come out saying something like "iTunes needs to be updated to 8.2 or iPhone cannot be used" (Something like that...), ignore that, take your iPhone, make sure it is connected and turned on, and put it into DFU mode by pressing both power and home button for 10 seconds, then let go of the power button but keep holding the home button for about 8-12 seconds, until you hear the USB sound from your computer or some pop ups will come out saying your iPhone is connected.

5.After a few seconds iTunes will say "iPhone detected in recovery mode and needs to be restored", press ok and then it will show you a new page, press shift+right click on the 'Restore' button, and look up the iPhone 5h11a restore.ispw file and press ok.

6.Wait for the iPhone to be restored, this time it shouldn't give you any errors.

7.After it is done, you have 2.2.1

Jailbreaking and unlocking

Turn on quickpwn, look up the ispw file, and continue, follow the instructions, and if you want to unlock, it will tell you to browse and upload the bootloaders 39 and 46.


Have fun... Please give me credit...

WOW...nicely done with the Step by step...you put in some good work here. Now we just need someone to give us a confirmation....anyone want to try this and let us know

Nope same error 1600 in DFU mode. Error 20 in Recovery Mode. At this myself for the last couple of days, trying everything, no joy

Originally Posted by Drustan

Nope same error 1600 in DFU mode. Error 20 in Recovery Mode. At this myself for the last couple of days, trying everything, no joy

That is impossible, i had the same problem and this is how I fixed it, you followed every step?

Can you walk him through this...

Originally Posted by TheDann

That is impossible, i had the same problem and this is how I fixed it, you followed every step?

Let theDANN walk you through

Originally Posted by Drustan

Nope same error 1600 in DFU mode. Error 20 in Recovery Mode. At this myself for the last couple of days, trying everything, no joy

Yes every step. I've my iphone from the beginning.
Modem Firmware 04.05.04_G. Can you confirm that your modem firmware is the same? I might be wrong but I'm thinking the firmware isn't compatible with v2 software?

Your firmware is very good...i have the same one...

Originally Posted by rugburn

Your firmware is very good...i have the same one...

Yes but from your sig you still have 3.0 installed, you didn't downgrade, no?

Ok, so I understand that this does not work for everyone else.

So now what I have learned from other tutorials is that by the time the 1600 error comes up, the firmware is already installed. So try to restore with iTunes 7.7 again and after it shows you the 1600 error, exit DFU mode by pressing and holding both the power and home button together for about ten seconds, it will probably go to recovery mode. Open up quickpwn and load up the 2.2.1 ispw. It should tell you if it matches your iPhone, if it does, continue the jailbreak, if it doesn't, tell me.