Next time, it would be advisable to completely zeroize your N9 beforehand so they can't possibly try to blame the problem on 3rd party apps. This would also help keep your data safe (by destroying it all ).

Zeroizing your N9 with flasher

Download Navifirm+ and retrieve main and eMMC images (the large files) for your product code and release 20.2011.40.4 (PR1.1)
Note: If you're using an imported N9, download your home country's eMMC or the generic no-maps-included eMMC

Install Flasher 3.12.1 (Windows version)

Open an administrative Command Prompt

cd "%programfiles%\nokia\flasher"

Disconnect the phone from USB and power it off

flasher -i

Attach the USB cable and quickly power on the phone, then wait for flasher to come back with the firmware version on your phone

If the phone has a low battery charge, leave it alone for a while

flasher -f -F c:\path\to\main.bin --flash-only=rootfs --erase-user-data=secure

flasher -f -F c:\path\to\main.bin -F c:\path\to\emmc.bin --flash-only=mmc

flasher -R

Power on the phone