Refer the below steps.
1. With Windows Explorer, copy the new firmware file in the following directory:
C:\Program Files\Schneider Electric\ PRM master DTM\ Firmware\
2. Rename it PRMOS.bin
3. In the Menu bar of Unity Pro, select Tools > DTM Browser.
4. In the DTM Browser, select < - >PRM_MASTER.
5. Right-click on it (Master DTM contextual menu) and select Connect.
6. Right-click on it and select Device menu > Download Firmware.

Refer below video.

Released for: Schneider Electric India