In any case from your description you have a defective power board part #N0AB6JK00001 ,namely weak/vented capacitors and those do not like to be left uncharged/unused for extended period .
You could possibly get the tv going again this time by unplugging it 20 secs and try it again and do this repeatedly up to 10 times but ultimately it wont turn on any longer will need to be repaired
Now this board will require some know how to replace it as it will need to be adjusted afterwards.
If you are into this i will find it for you and could help you along but you need to be comfortable working with circuit boards , otherwise you are looking at some $250 to have this repaired at home by a shop and you substract $50 to $75 if you take it to them
but if i may be frank , considering the age of the tv at 6 or 7 years old and the fact that you can get a new 50" tv with all the bells and whistles for around or less than $500 ,I would think twice before investing that kind of money into this one.
I think your money would be better invested in a new tv .
Here is a link where you can find repair shops ; www.tvrepairpros.com
This will give you a list of NESDA member repair shops in your area.
This list may be limited though and you may find more by simply using the yellow pages or simply google "tv repairs" and the name of your town .
If you have a choice do call more than one shop for a rough estimate , their rates can vary quite a bit .
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