Sat_Help, can you take it to Nokia Care & ask them to install the filmware for you? Or the Nokia Store/Dealer that you bought it from - In my country it's free to update if it's purchased at the Nokia Dealer (not talking about Nokia Care) & they open at night & weekends. Assuming you're in a country where N9 is released, they should be able to do it.
You trying to troubleshoot by yourself may cause more problems
Try to download the image again. It may be corrupted. And also restart your system. I dont know sometimes I am having those errors when flashing but restarting my computer/redownloading image fixes it.
you dont know what is upper n9 flash file in version 30 ?
You have already flashed the latest version (PR1.2) and as you already know downgrade is disallowed. Unless you want to wait for PR1.3 take it to Nokia care and let them fix it for you.
It that flash command was successfull and took some 10+ minutes, then you might have just bricked your device by flashing wrong variant (which didnt match your phones variant) to your phone. Nothing that you can do other than wait for next possible PR release or nokia care.