An auto injector for administering a medicament, the auto injector being connectable to an electrical power supply, the auto injector comprising: a housing accommodating a battery and a first electrical connector accessible via a connector opening in the housing and accepting a second electrical connector of the electrical power supply; a cartridge receiver configured to receive a cartridge containing the medicament; an ejector member movable along a longitudinal axis between a first ejector position and a second ejector position, characterized in that the ejector member is further being configured to follow movement of the cartridge along the longitudinal axis when the cartridge is received in the cartridge receiver; wherein the auto injector further comprises: a blocking member coupled to the ejector member, the blocking member being configured to move between a blocking position, in which blocking position the connector opening is blocked, and a non-blocking position, in which non-blocking position the connector opening is not blocked, wherein the blocking member is in the blocking position when the ejector member is in the second ejector position, and wherein the blocking member is in the non-blocking position when the ejector member is in the first ejector position, wherein the ejector member is in the first ejector position when the cartridge is not received in the cartridge receiver, and wherein the ejector member is in the second ejector position when the cartridge is received in the cartridge receiver. a housing accommodating a battery and a first electrical connector accessible via a connector opening in the housing and accepting a second electrical connector of the electrical power supply; a cartridge receiver configured to receive a cartridge containing the medicament; an ejector member movable along a longitudinal axis between a first ejector position and a second ejector position, characterized in that the ejector member is further being configured to follow movement of the cartridge along the longitudinal axis when the cartridge is received in the cartridge receiver; wherein the auto injector further comprises: a blocking member coupled to the ejector member, the blocking member being configured to move between a blocking position, in which blocking position the connector opening is blocked, and a non-blocking position, in which non-blocking position the connector opening is not blocked, wherein the blocking member is in the blocking position when the ejector member is in the second ejector position, and wherein the blocking member is in the non-blocking position when the ejector member is in the first ejector position, wherein the ejector member is in the first ejector position when the cartridge is not received in the cartridge receiver, and wherein the ejector member is in the second ejector position when the cartridge is received in the cartridge receiver. a blocking member coupled to the ejector member, the blocking member being configured to move between a blocking position, in which blocking position the connector opening is blocked, and a non-blocking position, in which non-blocking position the connector opening is not blocked, wherein the blocking member is in the blocking position when the ejector member is in the second ejector position, and wherein the blocking member is in the non-blocking position when the ejector member is in the first ejector position, wherein the ejector member is in the first ejector position when the cartridge is not received in the cartridge receiver, and wherein the ejector member is in the second ejector position when the cartridge is received in the cartridge receiver.