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If 24V not present at all it can be defective power supply.
If 24V present it can be the function cable preventing logic board enabling backlight by missing v-sync signal
Also check if 23-27V is going out the LED cable.
If no, check if some of the square inductors on top of the board (or components around them) seems overheated. It can probably also be another part of the board.
If yes, it can be defective LEDs inside the display assembly.
Checked voltages. 24V is present.
No voltage is going out to LED cable.
But I do have a strong clue what might be the problem. There is sign of burning on the top part of the board where a mosfet and a diode is located. Checked the diode and it is shorted. (Not sure about the mosfet yet)
Problem is I cannot find the characteristics of the diode. The serial number written on it is irrelevant. Cannot get a replacement this way.
Anybody has any idea what kind of diode is that?