Tcl L42e9adf tv half screen black at startup will go to full screen after 1/2 hour

I'd start by testing the 12 volt rail at the timing board, see if it drops as the set goes to a black screen, if so, unhook the panel ribbon cables, if the voltage stays your panel is bad and the set isn't repairable, if it still drops off replace the tcon board

If you hold a flashlight to the screen at a 45 degree angle can you see an impression on the screen?

Led strips need to be repaired or replaced ,

https://www.youtube.com/watch?v=KaKi5aC9fUQ

2010 was the year of release. It was listed by Choice, Australia's Consumer Reports, at a price of $1499. It was not a 32 inch but a 42 inch. That is what the 42 stands for in the model number. By November 2010, a discount site was selling them for $689 but that might have been an advertising trick. The manufacturer is a Chinese company. Here is its user manual: https://www.libble.eu/tcl-l42e9adf/online-manual-328111/
Here are parts: http://www.mxmee.com.au/index.php?route=product/manufacturer/info&manufacturer_id=1244

It's faulty and needs a diagnostic check. A cautionary tale...

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

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re program its flash memory if the problem remains same,get to any authorized setvice centre

Codes for TCL are; 0038,0031,0039,0033. Check these codes. If you wish to get more details, check the sites linked here. Setup code list, and setup procedure to many popular brand remote controls are given. http://electrohelponline.blogspot.com/ http://remotesearch.blogspot.com/ Selecting the view option, either to Mosaic / Time slide, can be selected by the drop-down list, at the top left of the display window, will make surf easy.

1-to solder vertical integrated circuit 2-see if any electrolitic filter is blow up-or 3-verify +24vcc 4-replace all electrolitic-filters.

T'Con board is faulty. Should be replaced.

you need to replace y-sustain board.