We got our power supply now but the Roku just blinks its white led light and does not show anything on the TV. Tried pressing the reset button on the Roku but no joy.

You could try downgrading the firmware by pressing Home 5 times, FF 3 times, Rewind twice then Choose Update Software to see if this downgrades the firmware to the previous version.

You could try seeing if there are any logs from the Roku by connecting via telnet. Replace roku-ip-address with the ip address of your Roku and run the following from the Windows run prompt:

telnet roku-ip-address 8085