SamyGO

I entered in sub menu of service menu where something showing "wait" for quite long time and I unplug the ac cord to force stop.
After that I plug the ac cord I shocked the power light is not blinking. Several times I plug and unplug the ac but no power light.

Could you pls advise how to fix this?

I`m almost sure you pressed "Micom upgrade". And this killed your TV. You can search this forum and you will find here is only solution which might work: ISP programmer and proper micom firmware. And even if you have required tools at hand, here is no guarantee you will succeed. Really bad decission to touch micom...

Another solution is to search second hand(cheaper) or new mainboard on ebay, local repair services or somewhere else, replace it and enjoy watching.