Sorry for a possible stupid question but i don´t think i used this "fusee.bin" in the past...Delete your Atmosphere folder, copy the new one over (1.4.0) and use the NEW fusee.bin file. You can't use the old one to boot the latest version.
I´m looking at my last year´s files (didn´t update this year yet, planning to do it now) and the only .bin file i found to use in tegrasmash is "hekate_ctcaer_5.6.2.bin". Is this an alternative to fusee.bin? (of course i´ll use an updated version of hekate_ctcaer_5.6.2.bin when hacking with 1.4.0 atmos)