KOT49H.N900AUCUCMLG is in the build.prop
you must still be on the MLG leaked KK
the MLG leaked KK is to get your phone going
you need to install the NC2 Kernel
then you can root with TR (towel root)
then install busy box and then safestrap
then install SuperUser
you then need to install the NC2 stock rom, that will get you close as you can get and change the KOT49H.N900AUCUCMLG to KOT49H.N900AUCUCNC2. the modem only changes the base (radio to NC2)
then after rom is running, uninstall Recovery from inside the safestrap app
the uninstall safestrap app
then use Superuser to remove root
then you can go to bestbuy or AT&T
All link to file you need is on
[AT&T][NC2_Bootloader][N900A MGL KITKAT][Stuck Download-Mode FIX]
the root stuff and this thread here is at bottom of that OP