Thank you for posting your question on Just Answer! I will be happy to help you with this problem. Can you please give us some more information so I can better answer your questions.
-What does the light on the front do when you try to turn it on?
-When you say good power supply, do you mean the supply in the tv or the outlet it is plugged into?
-How old is the unit?
Please give me this information and I will be happy to assist you further.
There are a couple of things that could cause this, unfortunately there is no reset for this television other than unplugging it. It will have an internal failure at this point. I will try to explain the possibilities the best I can.
First you could have a failure in the power supply, we have seen some capacitors fail in your model and cause funky problems like this. If this is the case you could be looking at somewhere around $175-$200 to fix the set. IF the power supply had to be replaced you could be looking at $350
Next could be the main board, this would not be good news because you could be looking at $400-$500 for the repair (I know this is up there in the price range and most likely getting over the cost of a new set)
Lastly you could have a bad AC fuse, however this would be rare unless you have had a storm or a power problem lately. If the AC fuse is bad a tech will normally charge $125 in your home to fix it.
Any of these could cause your problem, but it will require troubleshooting to determine the exact cause of your problem. If you have experience, and test equipment and would like to attempt some troubleshooting I will be happy to assist you, however if you do not have equipment or experience then you would need a repairman at this time to get an exact diagnosis. I am sorry that I don't have a quick fix or easy answer for you on this one, it is definitely an internal failure.
If you would like any additional information or have more questions please don't hesitate to ask!
Please never accept an answer until you are 100% satisfied and feel you can leave positive feedback. If I have answered your questions and met your needs then please press the green "accept" button. Otherwise please feel free to ask anything else to get your problem resolved. Positive feedback is always appreciated! Thank you,Tim Nolan