Thanks dc42. I have sent the board for replacement to Aururum. Due to easter holidays it will take upto 2 weeks till i get my replacement. Once i get the replacement, i will give an update.

I bought the Duet 2 Maestro from Aururum Australia to upgrade my CR-20 Pro printer.
Started the setup, Used the startup guide to connect via USB to computer. Everything worked fine.

Disconnected and wired the 24V supply and connected to network with network cable.
Switched the board on. The indicator lights came up and board worked for around 30 seconds before the U3 chip glowed and went up in smoke.

came across following posts
https://forum.duet3d.com/topic/9421/u3-buck-ruptured-admin-please-advise/3

https://forum.duet3d.com/topic/9212/duet-wifi-board-sparked-on-first-time-usb-connection

Here is the picture of the Chip. it is similar to one in above posts.

Please advise what to do.