No picture only sound.

Sounds more like LED backlight than a main board issue

It need to be service because the problem is from the display panel

I don't know your TV but are you sure that it is an "LED" TV? If not, it may be an "LCD" TV which is a bit different. An "LED" TV uses Light Emitting Diodes to illuminate the individual pixels or PIcture ELementS. If it is an "LCD" TV, the picture works more like an electronic digital watch. The picture is produced within the screen and uses a florescent tube on the bottom and side to back light the screen. If you can see the picture with a flashlight, I suspect that it is an "LCD" type. If it was an "LED" TV, and it didn't light up, the LED's that make up the pixels wouldn't be firing and you wouldn't be seeing a picture even with a flashlight. Just like any florescent light tube, these "LCD" back light tubes will dim with age until they eventually fail. If the Toshiba logo lights and goes out, this sounds like the bulbs or their high voltage drivers are failing. Good luck.

T con board is the culprit.

It sounds that the settings have been corrupted. It will be best to contact the authorized service center to make this set right. Beware, not to make any experiments hereafter. It's 'PHILIPS'

main board problem , please replace the specific main board .

Change the vertical scan drivers.

IF PICTURE PULLS ON RIGHT ADJUST BRIGHTNESS AND AND TINT UNTIL SCREEN SHOW FULLY AROUND PICTURE