To help narrow down the exact files you need, please share a bit more context:
Run a brief diagnostic check. Verify that all connected inputs, outputs, and network protocols are operating at peak efficiency. nm368818 firmware link
If your device features an option to save configuration profiles, backup your current network rules to an external file before flashing the system. To help narrow down the exact files you
Protecting the device from vulnerabilities that could be exploited in networked environments. nm368818 firmware link
Keep holding the button until you notice the TV indicator LED blinking rapidly. This signifies that the N.M368.818 board has detected the software and is writing it to the internal flash memory.