TCL TV FIXED Under $25.
Research, YouTube and Ebay... Fixed it myself. I needed an LED Driver (power supply/LED driver circuit board). My model incorporated both onto one single board.
Go to YouTube..... search and learn on videos from TampaTech and ShopJimmy.
As an aside: I mail-ordered a newer TCL TV from Sam's Club. TCL 43S453 is a 2022 model year. $219.88 plus tax plus $8 shipping AND this particular model is suppose to have a 3 YEAR limited warranty.
Or
Wait for the TCL 43 inch 2023 model 43S450R and aliases 470R; 410R; 430R to be available soon. The 2023 model has an updated display with Dolby Vision and the audio with Dolby Atmos.
Had I known $25 would fix my old tv...... I would have likely waited for the 2023 model to arrive in the Roku format. The Roku environment / interface is highly rated and just works.