No Signal, No Wifi, No Carrier option in settings. please help

Hi all

I have searched the net for 2 months now and still can't find an answer, i start form the begining and hopefully someone can help.

I have an iphone 3g, which i upgraded to the Ipad BB 06.15.00 using Redsnow 5 for windows, i did this in order to jailbreak and unlock the iphone using ultrasnow and ios 4.2.1 Everything worked fine.

I then decided to give the iphone to my sister, so I wanted to do a restore so it was liek a new phone for her. I read many forums explaining that once upgraded to the Ipad BB the only way to restore is to use a custom ipsw, so i downloaded a custom ipsw, used itunes to restore, this worked fine, now when i go into the phone, cydia is still there is no signal, and the wifi does not work either.

going into settings there is no carrier option. I have since read many forums, saying downgrade to ios 4.1 then use stock firmware, then jailbreak using redsnow etc which i have done, i used umbrella to kick it out of dfu, and still no joy.

here are the details of what is currently on the phone.

network: not available
version: 4.1 (8B117)
Carrier: not available
model: MB489B
modem firmware: 06.15.00

please can anyone suggest something fo me to try to get this phone working again.

like i said was working as good as gold until i tried to restore it for my sister. I have owned this phone from new and it originally came on the O2 netwrok