You should be able to upgrade directly to version 1.40.
Are you getting an error uploading v1.40?
A common problem is that users sometimes forget to unzip the archive before uploading (you would be surprised how often that happens).
I wish it's that simple, but unfortunately not the case of ZIP archive.
I failed uploading 1.10, 1.20, 1.30 and also 1.40, all failed.
Chrome shows it's uploading the binary, suddenly the position of selecting filename display "413 - Request Entity Too Large" and then upload stopped (seems upload still not finished), but the progress circle still running waiting forever except I press F5 and it returns to normal screen.
Firefox, IE10 also got same result, if nothing wrong with firmware, I'm suspect the hardware have problem.