Hisense TLM36H48 LCD TV has dark white raster and no image - Home Appliance Repair

Hisense TLM36H48 LCD TV has dark white raster and no image.
There are no characters but there is sound. First check the voltage on the logic board and check the screen power supply = 0V. Check its power supply circuit. Look at the picture
to check that point A of L15 = 12V and point B = 0V. Check that L15 is open circuit and replace point B with L15. =12V, U24: 5, 6, 7, 8 pins = 4.2V (normal 12V), obviously wrong, check C293 and there is no problem,
replace CA1 and everything is normal.