Cause of Firmware failure percentage?

I am trying to update my PS3's firmware, but the update kept stopping at around 67%. I finally got it to update, only to have it tell me it needed an even newer update. It didn't work that time. So now I wonder what percentage affects what. For example, I have heard that if it stops in the 60-70% range, it is a problem with the Blu-Ray drive. Anyone know the full list?