Connect your computer or phone to the DWR-M960 network (via Wi-Fi or Ethernet cable).
A firmware flash will reboot the router. Do not do this over a weak WiFi connection. Use an Ethernet cable to avoid a "bricked" device. Dwr-m960 Firmware
You cannot update what you do not understand. To check your current build: Connect your computer or phone to the DWR-M960
Only flash OpenWrt if you are a Linux expert. For most industrial users, stick with the latest official Dwr-m960 firmware. Dwr-m960 Firmware