Firmware Installation on Additional Snom M900 Antenna

Hello,
At one of our clients, we have already deployed around thirty Snom M900 DECT antennas, all running firmware version 530 B2.
We now need to add one additional antenna to the system, but I am unable to install the 530 B2 firmware on this new unit.
Could you please advise me on how to proceed in order to align the firmware version with the existing antennas?