Para volver a kit kat tenés que exceptuar los primeros dos comandos por fastboot
Estos dos
mfastboot flash partition gpt.bin
mfastboot flash motoboot motoboot.img
O sea,
mfastboot flash logo logo.bin
mfastboot flash boot boot.img
mfastboot flash recovery recovery.img
mfastboot flash system system.img_sparsechunk.0
mfastboot flash system system.img_sparsechunk.1
mfastboot flash system system.img_sparsechunk.2
mfastboot flash system system.img_sparsechunk.3
mfastboot flash modem NON-HLOS.bin
mfastboot erase modemst1
mfastboot erase modemst2
mfastboot flash fsg fsg.mbn
mfastboot erase cache
mfastboot erase userdata
mfastboot reboot