It really doesn't tell you which one. I can't know what electronics repair background you have and since there are lethal voltages inside, you take all responsibility to any harm you inflict on yourself.

My favorite is to remove power and unplug and plug connections to see if it's some failure similar to this video. A new tech won't see why this applies. The connections can do lines, solarization, and more. Watch at https://www.youtube.com/watch?v=WuwG5wqxTpE