I have a Nexus 9. Like a fool I was seduced by the pure Android experience and ordered this laggy crasshy monster.
I downloaded and attempted to install the latest security update over the weekend. The wallpaper had gone, and would not allow me to select a new or reinstate my wallpaper. I was not allowed to access any of my downloaded files and Bluetooth was unavailable.
I bit the bullet and instgated my first factory reset. The device went into bootloop. I tried to empty the cache, even wipe the cache partition, but was unable to do so as the device is locked.
No amount of pressing volume and power key combinations is going to change it's sorry state.
The Android boot wheels are dancing happily, taunting me.
The device itself is just over a year old. However, I feel that as Goog;e and carriers are meant to work together over security updates - they did in the old days at least - that O2 should take some responsibility for this.