I just want to say thanks the OP, as scary as this method seemed at first, this was surprisingly quick and easy.
Thanks for quick responses.
So apparantly I need to add "-i 0x1949" between fastboot and any commands, but i'm not sure why, i've never had to do this before. Is this something specific to the HDX ?
Good to know the version is irrelevant, tha...
I'm keeping my boxed until either 1) root, or 2) January 31, 2017 (last day to return if purchased between November 1, 2016 and December 31, 2016).
In the meantime, three years old HDX are looking better and better...