Old thread I know but I recently had the same problem with my 2011 Macbook Air. The QWERTY row was dead BUT would, on occasion, return to full functionality. I invested 6.95 in a set of nice quality tools for back and battery removal and went ahead and removed the aforementioned bits. I left the battery out and disconnected for 24 hrs and also pressed and held the on / off button for a few seconds. On re assembly the Macbook is working perfectly and back to its old self.