Richard has a Google Nexus 9 and signed up for the beta program for Google N, but he can't get past Google. Has be bricked it? Leo says no, he can't really brick it that way. Leo says to go into recovery mode and back out of it. He'll also have to wipe his data and cache. Richard will have to download the drivers, do an ADB, and then download and install the Nexus 9 image. He can also try reinstalling the N Dev again, since maybe it was a bad download.
Leo also suggests going to XDA-Developers. Richard will find some good advice on how to fix this issue there.