This update was going fine for 2 days, but my savedata and some games dindt boot or were corrupted. Then I was hearing music and suddenly no sound on my psp. At first I think my psp broke, but I remember installing the firmware so after trying everithyng (turn off, on, vol up, down, battery out, in) but still nothing.
Finnally I decided tht it was best to go back to 5.00m33, and the sound was back, savedatas were fine and games boot fast and normally again.