You have started and connected to the deCONZ GUI that means the FW is installed correctly and the RaspBee is working. There is a bug in GCFFlasher that sometimes it says firmware flashing was not successfull although it was successfull.
On the screenshot you see the coordinator node (the RaspBee) with the network address 0x0000 which is the default for coordinator nodes. So all is fine.
You can check the currently installed firmware bei clicking at “Help” and “abaout deCONZ” in the GUI.
(or with the GCFFlasher command “GCFFLasher_internal -r”) The newest version is the 26720700.