LG 42LB5610 LED TV - Matrix Backlight Issue, Bright Spot, Diode Replacement, & Repair Options

Good morning!

I have purchased, used LG 42LB5610 LED TV - from two weeks on the matrix was visible (only on very bright or white scenes) such a sunshine, as if I was shining in the matrix behind the flashlight. A bright spot in the middle with a darker border.

Yesterday the matrix went out completely - the sound is on, I also shone a flashlight on it - you can see the contours of the menu. When turning on the TV for a fraction of a second the LG logo is visible, as if for a moment the matrix lit up.

I bet that one diode has been dropped, because they are connected in series, right? If I am wrong, I am asking you to make a mistake.

Will I be able to replace the diode with a rather poor concept, or should I bring it to the site?
I do not want to be cut in the service, for some increased costs or replacement of unnecessary parts.

In case of damage to one diode, do you replace whole panels or only damaged LEDs? How much of such "pleasure" should it cost?

Thank you in advance for your response!

You probably have the matrix HC420DUN-VAHS1. 8 strips of 4 LEDs. Strips type LG Innotek DRT 3.0 42 "(diodes 6V) there are 2 types of strips A and B. At the auction want to strip about 25-27 PLN. It is better to replace the strip, because probably one LED has been blown. However, you need to check all the other LEDs. You did not advise against this, because if you do not have enough experience, you can damage the die when you disassemble the panel.

I had a similar case, and it looks like a colleague aptly described the problem of the lack of backlighting. In my case two LEDs were blown on two different strips, initially I tried to substitute any diode to confirm whether it was the only malfunction, it turned out that the TV started up and everything would be fine except for the color and angle of lighting of the inserted diodes. The next step was the purchase of used strips (not necessarily identical) that became the giver of LEDs with the same parameters (while I have a stock for subsequent repairs). For disassembly it is worth using a hot-a laminate is also a "radiator" and it is quite hard to solder without damaging them. It is worth purchasing a two-component adhesive to attach "lenses" (collimators) and I am sensitive to the precision of fixing them, any flaws will result in shadows on the matrix.
And one more important matter, if not the most important disassembly 42 inch matrix (glass) is best done in two people because it is easily damaged (it is about 2-3mm) and combined with the surface is easily bent, of course, do not forget about tapes (flexes) on the bottom and side of the glass because it is easy to damage them. It's true that I was doing a 42 inch matrix myself but I will not say that I would not sweat at it. I recommend using gloves to not leave any imprints on glass. To make it so easy to check it out, if there are such elements:
https://www.elektroda.pl/rtvforum/topic3276724.html
Good luck

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I have such a TV after turning off did not turn on the varistor and the thermistor are ok fuse too What could happen? Please help.