Don't worry about it...that's normal when the logic board is replaced. If you need the serial, it's on a plate somewhere on the machine...usually inside the battery bay.
Oh I know. I wrote it down, but it some applications it gives me incorrect age of the computer like 30000 months old or something. Is there a way in the terminal to add the serial back in?
It only holds 59% capacity because it only holds 59% capacity. Coconut (as far as I know) doesn't really care how old your computer is when it makes that calculation.