If you want to flash your n9 you must make sure your phone is turned off...To be on the safe side press the power button for 8 seconds to turn it off when its on... Just use flasher to flash instead as there will be an output if there are any errors... If you want to fix your n9 without flashing instead I need you to post the output of apt-get autoremove and apt-get update here to guide on fixing it...