Time to call your local Samsung office and arrange for a tech to fix it. Even outside warranty (you didn't tell about that) you might be able to get a free repair.
.factory reset..and restart steps. After restarting the TV showed setup process with 5 steps. Things went well upto 3rd step. But at 4th step which "Select the source of your TV signal" the TV froze. No response and I waited whole night but the setup process stuck. I am frustrated, What can I do now? Please suggest me. If this is the bug in Samsung TV software then I wont recommend anyone to buy samsung products.