@dw57978 first you need to rule out your inputs as error source. Remove all of them (especially if you have some sort of cable box, sat box etc.). Unplug your TV and unplug all input sources. Hold down the power button for 30-60 sec. Then reconnect one input source (preferably local, something like Game console, DVD/BR player). and make sure you use a known-well HDMI cable, if that's how you connect. Lastly reconnect the TV and try to turn it on. See if that changes anything.
Next remove the back cover from your TV. Let's see if your power supply works. Disconnect the main board from the power board and connect the AC cable. Something like done in this video up to 0:30.
If your back lights come on you know your power supply is good. Also see if the start-up behaviour has changed. Next you need to see if it is a T-con board error. Reconnect what you disconnected first. Then unplug the T-con board (small green boar that has one flat ribbon cable going to it from the main board and two going to the panel. Disconnect the one flat ribbon cable from the main board. Behaviour changed?
Not sure why your main boards have such a different startup but we assume your new one as working order. Last but definitely not least, measure the voltages on the power board connector where the cable to the main board connects to. Let us know what voltages you get.
It will help if cour can post some pictures of what the boards and interconnect cables look like. Take one picture of all of that and then a picture of each individual board. Pst those with your QUESTION. Edit it and use this guide 기존 질문에 이미지 추가하기