Bizhub-C-253, User and Administrator mode

Bizhub-C-253, User and Administrator mode.

Have only very limited experience with this machine until now. Customer called me that he purchased a used BH-C-253. When selecting user mode it shows only entrance # 4 and # 6 no other options available he told me.

Question: How to reset the machine back to factory settings or how at least to enable the full user and administrator mode. I have the tech manual but it will take me half a day to find it out myself and I have to answer my customer early Monday morning at 7:00 AM. Problem is I have no machine at hands to figure it out by testing.

Thanks in advance.

Hans