deSede Armchair in select Black need help!

[SimonCHAN]

I have a deSade armchair bought in 2004. In recent years, cracks developed on areas frequently seated on and leather lost its suppleness.



Last year, I had applied some leather cream/wax to prevent further deterioration.



Now, I want to restore the damaged area and take better care of the remained area.
It is in black Nappa leather with light pigmented. From the leather sample, the back and cross section are in black.
I have put some water on it found water would not be absorbed.



Please advise how to restore the damage areas, bring back the suppleness and what is best to maintain the leather.


Thanks,

SimonCHAN