Subtle flicker in tv backlight

Hi, I have a Samsung UE40H5303AK television which has a subtle flicker in the backlight. The leds go up and down slightly in brightness and from what I’ve seen the flickering becomes less severe after having the TV powered on for some time (although I’m not sure). I’ve measured all the pins on the PSU when on and off and it seems to be working perfectly and so does the main board. Could this be a problem with a capacitor or maybe a diode on the PSU? the only pin I haven’t measured is the BLU_PWM so maybe the main board is sending an unstable PWM signal. I’ll try to measure it with an oscilloscope and see if I see anything strange.

one more thing to add, backlight voltage across D+ and D - is around 120v and I have multiple broken leds on the backlight (one of the three strips only has 1 led working!)

Any help would be greatly appreciated.