Bear in mind that the phone itself also checks the word (2-bytes) every 20h of the flash.
You are right that the checksums of 13 54 21 and 15 53 20 are the same but let's say "13 54" happens to be in one of every 20h of the flash.
So the changed "15 23" would cause a no network and phone resetting if not for the ever famous "Contact Service". |