Sony Bravia KD-65X9000F (X900F, X90F) doesn't turn on

Hi Folks

I am posting this in hope that somebody can point me in the right direction.

I own a Sony TV (65 inch model of X9000F or what is elsewhere in the world known as X900F or X90F). Unfortunately, in order to protect it from a storm, I decided to unplug the TV from the power source and after the storm passed by, I wanted to plug the TV back in the next day, only to find out that the TV doesn't turn on.

Somehow, I have a hard time believing that this would be caused by the storm, since I definitely unplugged the TV before the storm reached us.

The TV doesn't turn on at all - there are no lights that would turn on. Nothing happens after pressing the power on button, either on the remote or on the TV itself. I tried every possible troubleshooting I could find - leaving it unplugged overnight, performing a manual hard reset, etc.

Yesterday, I had an electrician who had a look at the power board - he checked the 12V output towards the main board and all seems to be fine on the power board. The electrician stated that he is not very comfortable diagnosing electronics, but according to him the power board was okay.

This leads me to believe that the main board is at fault, but before I decide to spend 250USD on a spare part, I wanted to ask you if there is something I can do better to find what the culprit might be.

I tried unplugging the main board from the power board (based on what I found on the forum here) with a hope that the backlight will turn on, but in this case it didn't happen. I am not sure if the troubleshooting I found was valid for different model. It seems like there is a lot going on the back of the TV (picture included).

Is there anything I can check? Does the symptoms (no turning ON, no standby lights) indicate faulty main board?

Thank you!