Dell Edge Gateway 3001 not connectable with ssh after installing Ubuntu Core OS

I was successfully using a Dell Edge Gateway 3001 over ssh (since it does not have a console output) till yesterday.

Now because of some problem, I tried to flash a fresh OS image on my device.

I downloaded .img and created Ubuntu core 16's new boot from the page that was generated on providing my service tag..

Then I tried to flash the new OS on device by following the steps mentioned in Dell's website.

But while the OS image is being copied to device's flash(step 4 in the link), my device's power LED showed solid amber colour instead of solid green.

Finally after boot-up, I'm unable to connect to Dell Gateway over ssh. (No other IP is displayed in my network)

Please let me know what could be done to make the ssh connection so that I can continue with my work.

Thank you in advance.