TCL model L40S4690E. Why does TCL logo appear on screen and nothing else happens?

I have a tcl TV 48 inch led the logo should show for about 7 seconds then go off and picture should appear

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.