flickering screen replaced t-con board

My TCL 55s401 TV started out with a flickering on the right side almost like when you would play with the horizontal hold on an old TV. Then it spread to the whole screen. It does it randomly, and inbetween the picture is perfect. I tried running the TV with the cover off and putting pressure on different spots to try and find a cold solder but couldn't. I replaced the t-con board but it made no difference. What would the next step be?