Why is my TV not catching the digital signals?

I have a Samsung UN46d6420uf LED 46inch TV. It is 2 months OLD. i have 3 devices connected to my TV all via HDMI cables. Till last week there was no problem with the TV to display the cable's HD channels via HDMI cable. After a recent storm in Louisville, My TV is not catching the Digital signals from the cable box and not sure what happened with it as the TV displays "No Signal" Error message. I tried the following and everything was vain.

1. Changed the Cable box HDMI cable

2. Changed the Cable box to a brand new one

3. Switched the HDMI port on the TV

4. Updated the firmware and reset the TV

I have even tested the HDMI ports on the TV with other devices and various HDMI cables, all are working fine and i was told by the cable guy that my TV is not catching the digital signals.

PS - Recently i had a very close Thunder at my home.

The Main Board is gone in the TV. The technician has replaced it with a new main board. And now comes another Problem, The picture is totally expanded whenever the 3D is turn ON within my TV.

The new main board will be replaced again. Samsung said that they will replace the main board.