I had the same problem with my gen 4, until I plugged it into my Mac and it did the upgrade with no problems at all. It's not exactly a crippling issue (versus,

I had the same problem with my gen 4, until I plugged it into my Mac and it did the upgrade with no problems at all. It's not exactly a crippling issue (versus, for example, my three times and now permanently bricked Nexus 7, which needed to be reimaged using command line dev tools after borking itself with auto-updates).