Midway through the Mavericks installation, my Air shut itself off completely -- no warning or explanation, and it did not start up again until I was forced to manually switch it on, at which point it said it was forced to shut down due to an error. It then resumed and seemed to finish the update, but immediately thereafter shut itself down again, and now will not boot up at all. No chime, no white screen, no response at all -- there's the tiniest, almost inaudible click from inside the machine but otherwise it's as though the power button hasn't been pressed at all. I've tried the SMC reset, etc, still no response. Until this point, I've not had any problems with the Air at all -- the only hint of anything that's made me frown is that it sometimes reverts to the sleep-mode black screen for a second or after I wake it from sleep. Nothing else at all. I also ran the Mavericks update on my rMBP, and likewise had no trouble with it at all. Any ideas what the problem could be?