Why is screen black SONY Bravia XR55X90J - sound works

Hi - The screen on my sony XR55X90j suddenly went black the other night whilst streaming a movie. The sound was still playing perfectly but no picture. ( No one had touched the tv when it went black - and there had never been any previous problems)

I have done a soft/hard/factory resets several times with no change. At one time the power LED at the front blinked red 5 times. However, most of the time after the reset when I turn the TV turns on (either from the power button under the tv or the remote) I hear the noises chiming (for the menus changes) when I try to change input or press buttons on the remote - but still no picture.

I have followed some simple diagnostics online to try to narrow down the problem but am now stuck.

There are no faint images when I try the flashlight test so I guess the backlights are still good. (When the tv is turned on there is a faint deep blue/black colour)

I unplugged and replugged all the connectors between the T Con , Power board and main board and all seem in good condition.

I disconnected first one, then the other LVDS cable between the TCon and main board - no change.

There is no obvious damage that I can see on any of the boards/connections ( either side of the boards)

From what I have read online it is probably either the main board or the T con

How can I check definitively which it is? I have a multimeter.

I live in a small island where it is not easy to get pieces sent to.

I am not an electrician but am capable of attempting most repairs with instructions.

Thanks in advance. Dave

OverView

Power Board

MainBoard

Main Board serial number

T-CON

T-CON

Not sure what this is LCOM - 9005104 was written on the protective plate holding it in position in the middle of the tv.