After about 3 seconds of powering the tv on, it starts to constantly blink. What could the problem be?

U have all the tools and know basic electronic also can do basic soldering work?Yes.Tv have power supply board problems,that the board where the power a/c cord plug into it.Take the tv aparts,check the tv power supply board carefully and replaced all those components capacitors parts that bulges up or puff up onto it tops.Or try website like Ebay.com to buy a whole refurbish power supply board for the replacement.Tv will work again,after power supply board is fixed or replacememt.