A method for opening a compartment door of a compartment of a parcel locker using a pin pad, the parcel locker including a plurality of compartments including compartment doors with lock units for controlling access to the plurality of compartments, a parcel control unit including a short-range parcel communication unit, and an autonomous pin pad unit comprising a pin pad, a pin pad energy storage, a pin pad controller, and a pin pad communication unit including a short-range pin pad communication unit for communicating with the parcel locker, and a long-range pin pad communication unit for communicating with a distribution server, wherein the autonomous pin pad unit
- receives a user pin code;
- matches the received user pin code with one or more pin codes stored on the autonomous pin pad unit;
- transmits an electronic token to the short-range parcel communication unit as a function of a matching pin code, wherein the electronic token will cause the parcel locker to unlock a compartment door;
- and
- receives an electronic synchronisation token from the short-range parcel communication unit.