TCL Smart TV Picture Very Dark Issue Fixed 

This is definitely not a T-CON issue. If you know that the replaced power board is good. then there are two possibilities. 1. Main broad issue (the board is not able to control backlight LEDs - 1% ) 2. LED has issues (This is the most possible issue - 99%)

First you need to figure out whether this is a LED back light issue or power supply issue (LED driver circuit). To do that follow this video (ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6CVT9-Lts4o.html) and find whether there is any damaged LED's in the LED backlight strips. If all LEDs are good you can make a decision that the LED driver circuit has a fault.

@@tech-corner2556 thank you for your response. The initial problem which was fixed by motherboard replacement was that the even though power was reaching the TV it was not switching on with the remote button or even the buttons on TV. Within a month this other problem occurred where first the image froze and then faded away from the sides to the centre becoming green then black. Could hear the sound but no image. Could fix this by doing main power off n on. But now TV is not coming on only from remote or TV button.

@@pallavisharma8773 Most of TCL TVs are turning on and can hear sound even though the backlight failed. This seems a different issue. As the first step do a quick reset to whether it works. - Remove the main power cord from main power switch. - Then press and hold the power on button on the tv (not the remote) for around 20 seconds. - Then release the power button and connect the main power cable back. - Then turn on the tv using remote or tv power switch. If the above reset does not work, follow these steps. (DON'T TOUCH POWER BOARD COMPONENT. IT HAS HIGH VOLATAGE EVEN THOUGH YOU ALREADY REMOVED THE MAIN POWER) - FIRST REMOVE POWER CABLE FROM THE MAIN SWITCH. then remove back cover and unplug all cables from main board to power and main board to T-con and main board to back side buttons, etc. and connect them back. (don't forget to clean ribbon cable ends using a soft cloth+alcohol or clone.. - Clean all boards using a smal brush (paint brush will work). If the above step also does not work, you have try software update. Follow this video for that > ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-cd2fQuO4S8o.html Good luck. Let us know the results.

@@tech-corner2556 thank you again for that very detailed response. I will have to call in a technician as I'm afraid I'll mess up something. But I'm inclined to try out ur detailed instructions. Will let u know. Where r u based if u don't mind telling here?

@@pallavisharma8773 OK, Good luck. Im from Australia.

I have the same question

I never thought about letting it sit for a bit! Damn I may never turn my tv off again 😂 I’m joking I got an old replacement rn for the time being, I’m just trying to figure out an alternative to how or what could be the problem

After watching his video yes it’s what you should’ve tried

It’s expensive to fix the panels