Hi, could be the main board but first you need to look for swollen capacitors on the power supply, here is the process:
, the
solution to fixing your TV is most likely the power supply, if you are wanting to repair it yourself and can solder, it is most likely going to need (2) 1200 or 2200mf at 35volts electrolitic Capacitors, or you can replace the whole power supply. The back is held on with a few screws around the back and edge and then you need to pop the edges loose starting at the bottom side corners. once the back is removed the power supply is mounted inside a rectangle metal shield , remove the screws around it and the little ones going into the jack/input section (using a short philips there), there is a wire running from a
circuit board to the USB input be careful not to pull on it, unplug its wire from the CBA. then look at the power supply (top center board) the cylinder looking capacitors that are bad will be bulged on top, usually there are two 2200mfd at 10 or 25volts. changing them should get it working. A repair shop will charge you around $250 for this job, FYI
hope this helps
thanks
Eric I’m happy to help further over the phone at
https://www.6ya.com/expert/eric_ab7c09ec01841771