Can they legally refuse to open the door even though I have to the right to break the police seal?

My brother was found deceased in his apartment after a wellness check. There was blood found in the apartment, so a police seal was placed on his door. He did not have a will. Two of my sisters were on the premises when my brother’s body was removed by the medical examiner’s office. Two days after his death, my oldest brother, went to the buildings management office and attempted to get the keys, but was unsuccessful. My estranged, eldest sister went back the following day, also to no avail. When me and my two sisters, the ones who were there when my brothers body was removed, went there, the management office informed us that their attorneys had taken over and none of us could enter the apartment because the police seal was on the door. They also stated that they did not know who the next of kin was and that we had to prove that we were related and had rights to enter the apartment. I was only the power of attorney for healthcare, but I was able to get my brother’s death certificate and a letter from the medical examiner’s office to have the police seal broken on my brother door. As a courtesy, I went to the management office, located inside of the building, and informed them that I was there to have the seal broken and that I was told to call 911 when I got there. There attorney was there and she informed me that even though I had the right to break the seal, they still were not obligated to give the keys to open his door. I let them know what that we needed to get his personal effects and clothing for his funeral and they refused. I was told by the attorney that there were too many persons of interest involved and that I needed his death certificate (which I had) AND a letter of administration from the circuit court before they will open my brother’s apartment. The seal is still on the door and I informed the attorney that I would not release it.