Hisense Roku black screen with working sound

A few weeks ago my tv stopped having image and just showed a glowing screen and I could hear the sound when I would move around on the home menu. After resetting the tv using the home 5x up 1x reverse 2x forward 2x method the image would come back, but periodically it would show vertical color lines of purple and sometimes green all over the screen then return to working. after turning off the tv for a while and returning it would go back to showing the same black screen. After a few days resetting no longer worked so I researched and replaced the tcon board but that didn’t seem to fix the problem although now resetting does work to restore the picture. I have a Hisense Roku model 65R6E4