The stars on the back of the e-card means that it has not been issued with an EHIC function, due to the conditions for issuing the EHIC not being fulfilled. The fields filled with stars “******” are deliberate to prevent the card being tampered with to give the impression that it is a full EHIC. Without entries on the back side of the card, it will not work as an EHIC. If this is the case you should apply for a “Bescheinigung als provisorischer Ersatz für die EKVK” (PEB) through your Krankenkasse.
Please note that the PEB is only valid for the holder of the card, so if you are travelling with a family (e.g. spouse/partner and children) you will need to have separate PEBs issued for them too.