Getting "Your device is corrupt." error message after MM upgrade

I flashed my Nexus 9 (Wi-Fi) to Android 6.0 (via manually fastboot'n the image files) and now when the device starts up it gives me the error message below. Everything is stock and its not rooted. The only thing of note is that when flashing the system.img file fastboot threw a failed to allocate error message so I used mfastboot to flash system.img instead. Any ideas on how to resolve this issue?

Your device is corrupt. It can't be trusted and may not work properly.

Visit this link on another device:
g.co/ABH


Sent from my Nexus 9 using Tapatalk

corrupt error message

I flashed android marshmallow using the nexus toolkit version 2.0.5 and now I keep getting a corrupt error message and I have tried flashing android marshmallow over it again but it won work, does anyone know how to fix it??