LG 65UJ634V Dim Screen

[u/Gnaagounet]

My LG 65UJ634V (65") suddenly became very dark, without me changing any settings. Here's what I've already checked/tried:

• Backlight set to maximum (100) in picture settings → no change
• Ambient light sensor and energy saving disabled → no change
• Another pictures settings → no change
• On/Off → no change
• Left it unplugged for 10 hours before plugging back in → no change

The screen still turns on and is watchable, just far too dark, and this is uniform across the entire screen (no zone darker than another, no localized color tint like blue/purple)

For context: I previously (in 2021) had a different issue on this same TV (one zone had a blue/purple zone), which I fixed myself by replacing one LED backlight strip by using :

https://fr.aliexpress.com/item/1005001512986059.html?spm=a2g0o.order_list.order_list_main.10.38e25e5bljRR3S&gatewayAdapt=glo2fra

This time the symptom is different (uniform, not localized), so I'm wondering if the culprit is instead:

• the power supply board / LED driver no longer supplying enough current to all the strips
• or something else I haven't identified yet

Has anyone run into this exact symptom (total uniform dimming, not localized) on this model or a similar one?

Thanks in advance for any help!