I tried to downgrade baseband's firmware from 1.0.2 to 1.0.0:
"./bbupdater -f ICE03.12.06_G.fls -e ICE03.12.06_G.eep"

It says: "Error: Failed to download .FLS: Could not verify downloaded image." And my iPhone is then bricked (cannot pick up any signal).

I tried to restore the baseband firmware back to 1.0.2:
"./bbupdater -f ICE03.14.08_G.fls -e ICE03.14.08_G.eep". And then full restore through iTunes to re-virginize the phone. But trying several times, the problem remains: cannot pickup any signal and says my previously activated AT&T sim card is "Not valid SIM".

Did I damage the baseband hardware by downgrading? That's horrible. Anyone can help or give suggestions?

Originally Posted by iphonekiller

I tried to downgrade baseband's firmware from 1.0.2 to 1.0.0:
"./bbupdater -f ICE03.12.06_G.fls -e ICE03.12.06_G.eep"

It says: "Error: Failed to download .FLS: Could not verify downloaded image." And my iPhone is then bricked (cannot pick up any signal).

I tried to restore the baseband firmware back to 1.0.2:
"./bbupdater -f ICE03.14.08_G.fls -e ICE03.14.08_G.eep". And then full restore through iTunes to re-virginize the phone. But trying several times, the problem remains: cannot pickup any signal and says my previously activated AT&T sim card is "Not valid SIM".

Did I damage the baseband hardware by downgrading? That's horrible. Anyone can help or give suggestions?

Are you using a Mac or a PC?
If PC try running iBrickr to get you past that "Not Valid Sim"
on a Mac I think its iActivator but you may want to double check that.

http://iphone.nullriver.com/beta/

If you have mac use the installers on there, they should restore even though thats not their purpose.

Originally Posted by ShawnH

http://iphone.nullriver.com/beta/

If you have mac use the installers on there, they should restore even though thats not their purpose.

are you saying apptap installer reflashes the baseband with original .fls and .eep ??

Tried. None of them fix the problem yet. They can remove the "Not valid SIM" error. But after that, the phone still has no signal. My AT&T sim card was truely activated before. So it's not an activation problem. Instead, I'm worried about the "no signal problem", which means the phone cannot contact any network to send/receive calls, even after activation and unlock. If that is true, then we have to be serious not to downgrade the iPhone firmware. It appears that downgrading may cause your phone to malfunction.

apptap installer does not reflash *.fls *.eep.

I was following some popular online guide saying if you did anything wrong you can always reflash the baseband firmware with bbupdater, *.fls, *.eep to re-virginize the iphone. So I thought I should re-virginize it completely back to the 1.0.0 firmware state. Am I the only one in the world doing this silly thing? Anyone has the similiar experience?

reflashing the baseband manually can fix the no signal problem but I still don't know if you can fully downgrade

Why do you want to drop to 1.0.0?

Originally Posted by gaz919

reflashing the baseband manually can fix the no signal problem but I still don't know if you can fully downgrade

I tried: "./bbupdater -f ICE03.14.08_G.fls -e ICE03.14.08_G.eep". And then load the CommCenter. Or restart, Or restore. Still no signal.

You just need to reactivate...