I already tried that. I even deleted the current .ipsw file, with the Norton AV disabled; just incase of corruption.Hello ,, i have got the same problem and when trying the recovery mode and to restore my ipad , i have got the same error (-1) .
then i have stooped my running security software ( it is Symantec in my case ) , stop the service from the administrative tools/services in my PC. and trying restore process again . then my Ipad has been restored scornfully.
All still same.