That happens to me a lot, at the very last boss. Go a little lower than where you entered before. IF I remember correctly of what ShiningDragoon told me before that has happened to him as well. You enter the door to glitch it, is that your position where you entered was higher where you supposedly enter normally. Not sure if that helps but ShiningDragoon can explain better than me as we both experienced that part of the glitch where you got frozen.
I wonder if Zakky had that same problem too.
Basically just start the key glitch as low as possible. So go from a low position and spam press as you walk up. Or figure out that spot in general. I do the former
just got it, when the final boss change the song, just down to all, left and up a little to "mashing" A Button; 7 of 7 times no freeze, thanks a lot MrPupG & ShiningDragoon !!!