Toshiba screen black with sound (was flickerering previously)

Hi all, wondering if somebody could advise me if my tv is worth fixing?

Toshiba tv (Model - 50UL2063DB) started flickering in the bottom sections of the screen for a few weeks and then 1 day go to turn it on but the screen switches on but stays black (well a lighter black then when it's switched off). - screen then switches itself off after a minute or so.

I can hear sound in the background.

What I've tried so far, unplugging any devices and trying to get the tv menu up on the remote (Nothing).

Shining a flash light at the screen but see nothing.

Unplugging for a couple of minutes but still nothing.

Took the back panel off disconnected all the wires to the tcon board and other boards and reseated them, still nothing and no visual signs of damage (that I can see but I'm not clued up on tv repair).

I've read it can be either the tcon board or the main board that needs replacing, is it worth trying to replace these, if so which one is it likely to be?

Thanks in advance.

UPDATE - I removed one of the 2 ribbons on the tcon board and half the screen lights up as usual now and picture is back to 1 side but then does start going faint - does this confirm a tcon board problem? - please help