O.k then this is a LED tv and not much else but the power board can cause that sort of symptoms.
This board drives the power for the tv along with the LED arrays and it is not uncommon to fail .
I have been looking at possible suppliers for this board and to tell you frankly they are difficult to find in the UK .
I have the power board for the 55" model of the same serie and it could very well be the same power board but this would have to be verified with the supplier or perhaps if you could give me the numbers written directly on yours , it would start with the letters BN44....
You can see it at the link below;
Not sure if you had in mind to repair this yourself but this board cost around 50 pounds and to have a repair shop do this for you may cost around 150 to 200 pounds parts included.
Other than that it doesn`t look like that board is available at any suppliers that I could find in the UK but if you enter your poste code at the link below , it will list Samsung service centers near you where I`m sure you can get that board or simply have the tv serviced.
Here is that link ;
Wish i had an easier solution for you today ,like some sort of reset but this is not the case i`m afraid .
Hope this help and I will be in standby if you have any questions.
Thank you and please take the time to rate my answer if that answers your question and you can still reach me here at anytime after this chat is rated if you have other questions.
Please note that from where i`m sitting there is just so much that i can do and if you are going to rate my answer below O.K service then please do not rate at all , just let me know.