Some Pixel C owners have had a rough time with Google's flagship tablet. Problems first started appearing last month, when the scheduled over-the-air update for May (plus some Android N preview builds that had already been available) started causing semi-random reboots, usually when the tablet had gone into its low-power mode running on battery. The June update failed to fix the problem, as did the fourth version of the Android N developer preview.
It looks like we finally have a solution, but it's not a pretty one. After initially recognizing the reboot issue, Google employees commenting in both the AOSP bug tracker and the Nexus help forum haven't been able to provide a solution. A few desperate users (including our own Artem Russakovskii) decided to give up on waiting for a software answer and simply replaced their tablets. At this point all Pixel C units should still be well within the one year warranty. Lo and behold, the replacement tablets don't have the reboot problem, no matter what version of Android 6.0 or Android N they're running.
There's another solution, and that's to flash back to the April release or before. (Also note, not all Pixel C tablet owners are reporting the reboot problem, just a vocal collection of very upset people on Google's support sites. If yours is working fine, don't worry about it.) We're guessing that either there was a bad batch of specific Pixel C hardware... or that the reboot is caused by a cumulative problem with the tablet's design that will crop up on the replacement tablets too at some point. I suppose we'll know in a few months.
If you're ready to replace your tablet with the Google Store's RMA process, here's the contact information: