LG 55LB620V TV brightness not stable after LED change

[nmid]

Hello, a few LEDs were burnt out on my TV, so I replaced all of them with new strips.

Unfortunately, after reassembly I noticed that although the backlight is now working again, it is not stable. The top left LED bar is getting brighter every 2 seconds and then normalizes again.
Here is a video: https://giant.gfycat.com/QuerulousAmusingGossamerwingedbutterfly.mp4

Is my assumption correct that it must be the driver and not the strips? Could it be the half burnt out LED strips caused the driver to have a defect? Do any of you have a suggestion what I could try, otherwise the 70€ for the new strips just to have a defective TV would hurt me a lot.

Thank you very much for any help.

[eurgenca]

Could be first led on strip damaged.? Top left corner seems to be dark.

[nmid]

Thank you for your reply.

I do not believe, so I tried the LEDs when the LCD was still off and all LEDs worked.

But because of your post, I took another picture/test and noticed that on the left side of the screen the picture is a little stripy. So I suspect it might actually be the LCD itself and not the LEDs. I will try reconnecting the ribbon cables, but I suspect I might have damaged something when dissembling, which would be a huge disappointment.

https://giant.gfycat.com/OrneryCalmCalf.mp4
It's not really noticeable because of compression and refreshing.

[nmid]

So I am pretty sure it is not the LEDs, when unplugging the left ribbon it does not change brightness and I don't see it from the back as well.

So, anyone has any ideas what I could try? I have tried swapping the ribbon cables, pressing all ribbons and components on the signal board without success. The flicker is in fixed time intervals (~2s).

I appreciate any help. Thanks.

[nmid]

One picture is wrong.

[nmid]

I have an oscilloscope if that helps, but not much experience with it.