Obviously it needs repair. And, being out of warranty, I'm afraid it won't be free.
Are you really saying that neither the shop where you bought it nor Samsung is willing to do a paid repair?
My PN50C6500TF Plasma has just recently developed this power cycling issue that can be found all over the forums. I realize that the common resolution for this issue was to change the blown capacitors, but my TV is one of the "Slim" Plasmas, and does not seem to have user serviceable parts (all components are stuck/glued to the boards).
The only way for me to stop the clicking/power cycling is to unplug the TV from the power source.
I'm also concerned that this specific Plasma isn't one of the commonly mentioned TVs with the issue, and that so far, Samsung support has been less than enthusiastic about offering any help other than "Sorry, it's out of warranty." I bought this TV in 2011, and at just over one year later, it has developed a catastrophic failure. This is obviously unacceptable.
If anyone can offer any guidance or help on how to approach fixing my practically new HDTV, please feel free to chime in.
I've included a link to youtube that displays a video from my phone of the issue.