It wasn't bricked, it was just so slow that it couldn't get past the lock screen. Lots of people complained about it on the support forums, and you could get it to work better for a few hours if you got into the settings and cleared the cache, but it wasn't worth it at that point. There was talk of a fix in an update, but I never saw one. So no, it's not like an update burned up the charging circuit or something, it just made the device unusable.

I still use a 2012 Nexus 7 which runs Cyanogenmod 12. Pretty usable for occasional browsing and watching videos.