similar issue (image without backlight)

Hi, I have a very similar issue (image without backlight) but with a difference.

I checked the test points i n the logic board as per the manual, and there is something very interedting happening.

When I test them within 30 seconds from connecting the power to the plug, everything seems fine

After 30 seconds, the PSU fan seems to slow down, and the voltages change in the logic board:

DC in

TP11 =14.7 instead of 24.5

TP12= 0 instead of 24.5

TP13= 0 instead 12

LED backlight

TP81=0 instead of 25

TP82= 1.02 (OK)

TP61= 3.3 (OK)

I also check the voltage at the PSU (there is a cable in the board gettinh to the logic board with a 24v written on it)

Again, the first 30sec 24v , after drops (I dont remember how much)

Now, the interesting thing is, that when i connect the screem to my laptop, for the first less than a second ot flashes (i can see something) after that no backlight at all.

Im a bit confused, not sure what is wrong, and cannot spend money in changing everything. Im not sure if it is the psu, logic board or panel.

anyone help?