TV won't turn on after a period of use

@hostile17 we are going to assume that the power board works. Quick ( and very abbreviated) FYI and how this may work. It is the power board that supplies the voltages to the different boards as well as the LCD panel, but it is the Main board that tells the power board when and what to turn on. In your TV’s case it is possible that on or more of the IC’s on the Main board overheat and fail and thus the TV does not turn on. Sometimes your can use Freeze spray and see if cooling down the IC’s allows the TV to turn back on, other time a FLIR will allow you to see hot/cold spots and possibly determine which part has failed. you could also measure the voltages from the mainboard to the power board to see if those are correct. You would have to measure ones when the TV is cold and turns on and then repeat when it is hot and no longer turns on. At this point I would try another Main board if you do not think you have the tools/skills to troubleshoot the board. Of course post some pictures of that board as well as the T-con board (smaller board that connects via ribbon cable to the main board) with your Question. Let’s see if we can find anything odd looking. You will have to edit your QUESTION to add those images. Adding images to an existing question