The steps you tried sound nothing like I read in service manuals. You might be missing the service manual so check out samsungparts.com to see if they have it for your model. If not contact Samsung in your country. Remember I take it you are a TV technician by what you posted.
I have a samsung smart tv un46z7100wf,, with no nothing no picture or sound, I got a red light and did the test that I was able to find, I disconnected the main logic board from the power supply board and got no back light but plugged them back in and got backup light does this mean I need the main av board?, or is it the power supply. also I have power on the two ribbons on the top of the t-com board but at the bottom ribben going to the back light I couldn't get power, help please, thank you