i ran into this for the first time on a slim last night myself,switching to phat resolved it in my case.i know u most likley already tried that though,as this woulda prolly been the obvious thing to try. although,after working also with x360 pro v6 dual nand/glitch chip, i have issues with it where itll red dot and not boot on rgh nand,and on that chip,cpu_rst has to be juuuuuuuuust right or you will get a red dot boot every so often. try messing with cpu_rst