Just for interest are you flashing with windows or linux, 32 or 64bit and what kind of usb port?

I guess you have the right firmware variant for your device. Have you tried cold flashing the device?
I would try boot the rescue image and check the partitions from your N9 or make them new.

Repartitioning
Rescue

You could also try my rescue live image (see signature).

Just read following threads:

N9 Cannot be flashed........is it dead
Nokia N9 Failed to flash (this one is different some cmt issue)
Problems flashing Nokia N9 with Linux
N9 flash error ! Please help me( mmc0 failed)not booting device.