I had this problem just last night. It would not progress past file analysis. I tried twice, then checked the partition option, and it just shot through like it was waiting for me. My phone hung up on the lagfix disable (prior to flashing a new kernel, which I didn't get to), and so I'm sure something was up with the file system, which was why the partitioning was necessary.
The whole thing took maybe 10 minutes to go to stock, reroot, and reflash. But it took about 3 1/2 hours to try the less invasive methods, get all the right drivers on the right computer, and get to that point.