Sitting on the center of the Satellite crash site for the Code and base is killed

You must to have the base during those three days in the proper place where the satellite crashed. If your base is destroyed that time frame is reset. When you put another base, it will start over from scratch and you will have to wait three more days until you get the code.
It is advisable to provide some security to the base that you put to obtain the code, either with the support of other bases of yours or with other bases of alliance partners.