I asked the same question Samsung tech. support, the answer from them is below:
Thank you for contacting Samsung Customer Care.
After going through your email, I understand that you would like to know if the TV that you have purchased from retail outlet is a used once.
I would be glad to assist you with the required information.
Please do not trust any third party websites or the Forums as Samsung does not recommend them. It is not possible to check the time the TV was used. Only the Samsung certified service technician can physically diagnose and would tell if that is a used TV.
As you have received the closed box, TV should be an un-used and is tested by Samsung certified technicians at Manufacturing unit before its dispatched.
Samsung do not have any options to check the time of the TV used.
Please feel free to contact us if you need any further assistance.