The trouble of my tcl led tv was, everytime i use it, after several mins of watching, the tv turns off, even the standby light indicator turns off, what is the trouble of my tv?

Question edited for clarity 'make model (what it is)'.

How to Fix TCL Smart TV Remote - Support.com TechSolutions

https://www.techsolutions.support.com > how-to > how-...
Learn to solve common troubles you may have with your standard infrared and enhanced TCL Smart TV Remote.

TCL Roku TV: Wifi Internet Not Connecting? Try this First!!

https://www.youtube.com > watch
PREVIEW
2:47 I show you how to fix a TCL Roku TV (smart TV) where its not connecting to the wifi internet network (No Connection). By the end of this ...
YouTube · WorldofTech · Sept 16, 2020
Missing: 65R625 ‎' Must include: 65R625

TCL TV WiFi Not Working (Disconnects/Won't Detect/Connect)

https://readytodiy.com > tcl-tv-wifi-not-working-discon...
If your TCL TV WiFi won't turn on, press the 'Home' button on your remote control > press the right arrow button and select 'Network' > press the right arrow ...
Missing: 65R625 ‎' Must include: 65R625

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

Gettn it fixd maycost like newone. Googl or utube..

Sounds like The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

Its either an issue with the main or power board.

The red standby is on because the tV is not turned on. Once you turn the power ON the red led will go out and possibly another color will come on.

Sony TV LED & Blinking Codes - What Does It Mean When Standby/Timer Light Flashes

Sony has provided a "self-diagnosis function" with your TV, that in the case of abnormalities or problems the LED or red blinking light on the Timer/Standby indicator flashes a number of times to indicate the issue.
when there is trouble with your Sony Television set -- it indicates the issue in either the diagnostic mode, or even more commonly by flashing a series of LED blinks or flashes on the front of your television. Each set or frequency of the blinks indicates a very specific problem with the television itself.
Sorry but unless you may be able to repair the television set yourself , please call a local repair shop to the have a repairman sent out,,

Take care and please Remember to rate/vote for us to
continue for Helping out the Community :)

Sony TV LED & Blinking Codes - What Does It Mean When Standby/Timer Light Flashes

Sony has provided a "self-diagnosis function" with your TV, that in the case of abnormalities or problems the LED or red blinking light on the Timer/Standby indicator flashes a number of times to indicate the issue.
when there is trouble with your Sony Television set -- it indicates the issue in either the diagnostic mode, or even more commonly by flashing a series of LED blinks or flashes on the front of your television. Each set or frequency of the blinks indicates a very specific problem with the television itself.
Sorry but unless you may be able to repair the television set yourself , please call a local repair shop to the have a repairman sent out,,

Take care and please Remember to rate/vote for us to
continue for Helping out the Community :)

Sony TV LED & Blinking Codes - What Does It Mean When Standby/Timer Light Flashes Sony has provided a "self-diagnosis function" with your TV, that in the case of abnormalities or problems the LED or red blinking light on the Timer/Standby indicator flashes a number of times to indicate the issue.
when there is trouble with your Sony Television set -- it indicates the issue in either the diagnostic mode, or even more commonly by flashing a series of LED blinks or flashes on the front of your television. Each set or frequency of the blinks indicates a very specific problem with the television itself.
Sorry but unless you may be able to repair the television set yourself , please call a local repair shop to the have a repairman sent out,,

Take care and please Remember to rate/vote for us to
continue for Helping out the Community :)

From what I've been able to find, the problem is the fan that cools the bulb is not starting when you turn the tv on. Blow on it to get it going or clean with compressed air. The fan could be clogged up with lint etc. It's on the rear left of the tv.