You're talking about memories, self awareness is more than memories, it's about the learning experience that make someone who they are. Depending on the part being damaged, most likely their personality wouldn't alter if only the cerebellum is damaged, which would only affect their memory at most. Reprogram the synth would basically shut them off, taking away their consciousness, then adding new memories and personality, new background, which would make them an entirely different person, and the old self and old personality, and their background are all disappear. It's not the same at all.
I don't see how it matters, if it just means that person will be in vegetable state forever, the person is no longer exist if the memory and consciousness of the old synth is shut off.