Sonoff Zigbee bridge ncp-uart OTA update issue


I updated my sonoff zbridge (with tasmota formware) 12.5.0 version and I did a reset configuration.Unfortunately I am not able to be flash back the ncp-uart-nsw_6.7.9_115200.ota. When I try to update the mentioned fw I get the “Invaild signatute” error message. I tried the OFF mode and Module 75 command in the console window. How can I revive my bridge?