Firmware Update Anyway to permanently block the updates without jailbreaking?

I have a Kindle Voyage with the system version 5.6.5. Since I don't like the newly released system (5.7.2?), I was wondering is it possible to permanently block the auto updates. Also I don't want to put my kindle under airplane mode foever. So are there any other tricks? Thanks guys.

(I have googled and found a method that you can create a directory with specific names in the root folder when kindle is connected to pc, does it still work?—I have found some argues in this thread but I don't quite undersand them.)