Why can't I start up my Samsung smart TV? When I start the tv, the smart tv logo appears then blinks and disappears. Then the screen goes black and there are bits of pictures blinking all the time but no image. The sound is OK but there is no picture. It's been occurring on and off over the last 4 weeks. Sometimes, it works perfectly some other time I have to start the tv at least 5 or 6 times before I get the right image with the sound. Tonight, i have tried at least 15 times but still nothing

Cable connection problem: Your Samsung Smart TV is likely to have a black screen issue due to the cable connection problem. Loose connections, damaged cables or inactive power sources are the probable cause of the problem on your TV. ... If the menu appears on the screen of your TV, then the problem is with the sources.

go into tv set up see if on demo or store mode if ok possible bad control board

It has a reset button on the lower back right hand corner; push that button.

you have 2 caps gone on power supply 1000 uf 25 volt but use 1000uf 35volt

If the TV displays the menu or Smart Hub when you press the button on the remote - the TV is on, it's just displaying a black screen. Change the Source on the TV to another input. See the page on Samsung TV has No Picture for more troubleshooting steps.

Depending on the TV, there will be a Jog Controller or TV Control Stick that will allow you to access the TV menu and change the source. Use the control on the TV to select an option - toggle it left or right to see if anything appears on the TV.
If the control menu appears on the screen, the TV is on but not displaying any input. Check the connections or change the input source on the TV. If the controller button works on the TV, but not the remote, check the batteries in the remote control.

Unplug the TV from the power source and leave it for a minute or two. Reconnect the power cable directly to the wall rather than a surge protector. If the TV Standby light appears - the TV is receiving power. If the Standby light still doesn't appear, please get in touch to organise a service.

https://eu.community.samsung.com/t5/TV-Audio-Video/samsung-smart-tv-stuck-on-start-screen-logo/td-p/161506
https://www.samsung.com/in/support/tv-audio-video/how-to-turn-on-boot-logo-in-samsung-smart-tv/
https://www.cnet.com/forums/discussions/smart-tv-problems-with-youtube-600338/
https://www.samsung.com/au/support/tv-audio-video/why-will-my-tv-not-power-on/
https://www.consumerreports.org/privacy/how-to-turn-off-smart-tv-snooping-features/

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Pull up older posts.
https://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary. /

You have a shorted circuit board, which board requires testing.

Hello
Open your set, disconnect and reconnect all the connections
Probably a connectivity problem
Good luck

Test the power supply voltages and see if some are missing or incorect, if they are replace the power board