There is not much change between 49 and 53. Just the graphics of the dropdown menu and the fact that you can access it from any screen.
On the issue of not being able to load the ROM, a lot of people are having the same problem. I even had that problem the first 2 times I flashed. I actually rebuilt the ROM and flashed 3 times before it worked. I don't know why this is happening, but I know that the ROM I uploaded to you guys works for me. So, try reflashing some more or go back to an older build. Sorry, don't know what else to tell ya. You know there will be a new build in a few days anyway...
