Hi everybody

I bought a used n9 yesterday & that was working find but when i tried to set factory reset it asked me for security code . The buyer didn't put any kind of code & now when i start up the phone it demand a security code I tried to flash it many times but it still not work > Today the phone suddenly log in & i just have enough time to set usb mode to Sync . >

Is there a way to flash it without logging in ( dead usb mode) I tried but the computer didn't recognize the phone

Please Kinda crack to help me ?