I would try flashing android manually. It worked for me when I bricked my Acer tablet!
[link|https://developers.google.com/android/ota|Android OS Download|new_window=true]
If it is a Wi-Fi tablet, then you will need [link|https://dl.google.com/dl/android/aosp//volantis-ota-mob30d-1da7c803.zip|this latest version of android for your nexus|new_window=true]
You will need ADB like @aactech mentioned. Below is how to manually flash the firmware:
# Download the latest OTA image for the Nexus from that page
# [link|https://www.hardreset.info/devices/htc/htc-nexus-9-wifi/recovery-mode/|Reboot into recovery mode|new_window=true]
# Press the volume up and power keys at the same time to activate the hidden menu
# With the volume keys, highlight “apply update from ADB” and press the power button to choose it
# From your computer, execute ``adb sideload otaFilename.zip``