Can you go through this guide and let us know how far you get?
https://docs.duet3d.com/en/User_manual/Troubleshooting/Duet_wont_respond
Can you post some photos of the board? Perhaps we can spot some damage.
Is this a new Duet? Has it worked in the past?
Since this is a Duet Ethernet, you can create a config.g that enables networking at boot up and it should try and obtain an IP address via DHCP. You can check your router to find the IP address and then try and connect to it. This assumes the firmware hasn't been wiped.