Hi my name is Eric,
I can help you with your issue ,
Here is what it sounds like it might be:
Either the power supply has an issue , or you have a bad panel
See if the screen backlight lights for even a second.
The ilo powerboard may be hard to find, try ebay using the numbers from the board
or try checking it yourself for bulged capacitors or burnt connections that can be cleaned and soldered
A repairman will usually just order the boards and you will spend over $300 probably around $350
It could be just a few bad capacitors on the power supply, if you want to attempt the repair yourself you can do a visual of the power board caps will appear swollen on top.
Look at the photo I am uploading to see what a bulging cap looks like
With the back and any metal cover removed you will see a few circuit boards the upper or left one (ac cord runs to it through a small board) is the power supply, it has alot of capacitors on it (cylindrical standing straight up soldered in and marked on the sides with the positive/negative sides and uf and Voltage values)
Flat panels use 1000uf, 2200uf or 3300uf at 10v, 16 or 35Volts rating capacitors, they cost about $1-$2 each usually I replace two of them (or all the bulged on top ones) .
Buy caps here
The power board and back unscrew with a screwdriver , if you do not know how to desolder and resolder then do not attempt this as you may damage the TV more than fix it.
We do not recommend do it yourself, but depending on your knowledge and technical ability you may be able to.
You can replace the whole power supply, but there may be a few versions in these sets and some so called replacements won't fit due differences in the models,so make sure if you order a board you check the version numbers first
If you feel good about my solution please click accept.
If you have more questions you can still respond until this post expires,
I will reply asap