samsung un65nu6900f no picture no sound but backlights are working

I have a Samsung un65nu6900f for repair the backlight are working fine power board is also OK TV is ON but I can not see any video and sound on the Screen I Replaced the Mainboard there is no result, This TV doesn't have any Tcon board Replaced also two FFC Ribbons but no result the capacitors on COF board is showing short with the ground but it is not possible all capacitors are short with ground anybody has expertise in this fault, I can not says that panel is short