No, you can only restore using itunes.
Did you try using another computer with the latest itunes version installed?
What kind of iphone you're trying to restore, is it JB, does it have the ipad baseband installed, what firmware is it on now etc.....
yes i have tried that.
I have a iphone 4 jailbroke with greenpoisonRC5, running 4.2.1 and im not sure about the baseband..... the phone will not turn on and i cant get into DFU mode either, when i restore the apple logo and loader comes up on the screen then i get error 28. the phone definatly hasnt being water damage either..