Mainboard bad after replacing T con board?

I have a TCL LE46FHDE5300 that had backlight, sound but no picture. Researching online led me to believe the t con board was bad. I replaced the t con board and initially had a picture but then the picture faded until I got vertical lines over the whole screen. The lines faded until all I had was backlight again with no picture. Did I get a bad t con board or is the mainboard now bad? Any help would be greatly appreciated!!