i had the same experience too..
mine was razr maxx hd running stock 9.16.6 trying to run moto x's bootanimation
something wrong happened and got stuck in bootloop
reflash the phone to get it working again... using matt's utility (thx God for matt), fortunately i can still put it in AP fastboot mode
no more changing bootanimation for me though, unless i know how to manipulate maxx HD's internal files from AP fastboot mode