What may be the problem w TCL 65S4 TV only has a blank BLACK screen ?

Hello ! It sounds like you are experiencing some issues with your TCL TV. It's great that the backlight lights are working fine. The blinking *********** light and white screen definitely indicate a problem.
One possible issue could be with the internal circuitry or the display panel itself. It's best to contact TCL support or a professional technician to diagnose and fix the problem. In the meantime, you can try power cycling the TV by unplugging it for a few minutes and then plugging it back in.
As for uploading a video, you can try connecting your device to a computer and transferring the video file that way. Alternatively, you can upload the video to a platform like YouTube and share the link for others to view. I hope this helps!

There could be several reasons why your TCL TV is displaying a black screen after being powered on. Here are a few possibilities:

1. Power issue: If the TV is not receiving sufficient power, it may not be able to fully turn on and display a picture. Make sure the TV is plugged into a working outlet and that the outlet has power.
2. HDMI/AV cable issue: If you are using an HDMI or AV cable to connect your TV to another device (such as a cable box or a game console), the issue could be with the cable or with the device. Try using a different HDMI or AV cable to see if that resolves the problem.
3. TV settings: If the TV is not set to the correct input source or if the picture size is set incorrectly, it may appear as a black screen. Try pressing the "Input" or "Source" button on your TV remote to cycle through the available input sources and see if that fixes the problem.
4. Defective TV: If none of the above suggestions fix the problem, the issue could be with the TV itself. It is possible that the TV's display or some other internal component is defective, in which case you may need to have the TV repaired or replaced.

I recommend trying the above suggestions to see if they resolve the issue. If the problem persists, you may need to consult a TV repair technician or contact TCL customer support for further assistance.

Its either the backlight or the power supply to the backlight.

This the root problem of it.

https://www.fixya.com/support/r29790007-repairing_own_television

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When you had the panel out after changing the backlights did all the strips work before assembling it?

You have built a new television! This explains the issues you are facing and why it is happening.

https://www.fixya.com/support/r29790007-repairing_own_television

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Could be a faulty backlight assembly, could be a faulty invertor, could be power supply related ....

They dont list any LED strips and that may be a good thing: https://www.shopjimmy.com/tcl-55s403-complete-tv-repair-parts-kit-see-note.htm

https://www.shopjimmy.com/tcl-55s403-complete-tv-repair-parts-kit-see-note.htm

All symptoms in your TV shows that you need to replace its Lamp as it has been consumed its life hours and TV requires new lamp. Lamp can be obtained from Sony Website. Price is $200, Hope this info will help you to enjoy your Sony TV in coming days.