Hello,

I did not use my N9 since some weeks now so i may be a bit rusty.
But if i remember well, i got the same when i tried to upgrade the Kernel.
But it should boot anyway.

You should specify what you did before you got this.

If you tried to update the kernel, you should havea look at the firmware update wiki page to reflash only the kernel.

About the flash error, are you sure you use to correct firmware version?