7 blinks error Panasonic plasma TV

I have Panasonic plasma TV 42PZ800, it blinks 7 times. Searching around I got the tip that Y-SUS and buffer boards could be defect. A lot of people recommend replacing all of those 3 boards. I ordered new boards and replaced them but it didn't solve the problem.

I noticed that we I disconnect power cable of the Y-SUS board I get the same error, but when I disconnect the signal thin strip cable the 7 blinks go away and i get the fans spinning.

Any tips anyone?

Thank you in advance for your help.