It IS possible to downgrade from 2.0 5a347 to 1.1.4
You can follow this link which is very good (I found it after typing my HowTo):
http://sleepers.net/news/?page_id=216
Any way this is how I did it:
At first it gave me loads of trouble to downgrade but there is a way out if you have the tools.
Using common download procedures, DFU mode results in error 1600 and restore mode in error 20.
What I used (may not be required for everyone but worked for me):
MAC iTunes 7.7d31 at least
OS 2.0 5a308
WIN iTunes 7.6.2 (easier to switch OS than to reinstalling it to replace 7.7 and getting rid of any traces of 7.7)
OS 1.1.4 original
iLiberty or your favorite tool
MAC
iPhone-Virginizer
Pwnage Tool 1.1
OS 1.1.4 Custom Neutered
How I downgraded my 2.0 5a347
- I first downgraded to 2.0 5a308 with iTunes 7.7 (this method may expire if 5a308 expires). Why 5a308...? Don’t know, just chose it.
- Then I downgraded to 2.0 5a258f. Got error 1015.
- I switched over to Vista and launched iTunes 7.6.2.
- While in iTunes, I put it in DFU mode. (RESTORE mode wont work...) This part was tricky as it would not go into real DFU. It took many, many, many tries to get it to finally work. Make sure it is DFU otherwise iTunes will not start the restore.
- I downgraded to 1.1.4 and got error 1015. I tried to kick it out of Restore with iLiberty but only worked after installing again 1.1.4.
- I used
iPhone-Virginizer to downgrade the Base Band.
- At this point I Pwned and installed my custom 1.1.4
Finally got a working device with BaseBand 04.02.13_G (note: BootNeuter did give an error at startup that I missed reading, but I am fully working)