Samsung S27d590p monitor no brightness in some areas of the screen

I was playing normally on my pc suddently part of the monitor brightness went off, I could still see that section but less. Hitting or shaking the screen a bit would fix it or sometimes make it worse. Other areas of the screen might have no brightness. I tried opening the monitor, and I notice that the cable to the bottom of the screen from thr main board is VERY loose, not the male connector but in fact the frmale connector. I tried removing the connector, but the enire female connector went off (I literally didn't try it with any strength), as I mentioned it was very loose.

Anyway, I tried puting it back and pushing on the connector and the monitor goes back to normal but I had to push a bit hard for it to show up like that. The bottom area was also dead until I had to push a bit harder.

I took the monitor to a small repair store nearby; I have no warranty left. He opened it and soldered the female connector and as he said the connector is soldered correctly in place. Turning on the monitor, 75% of the monitor had no brightness, the backlight LEDs were off in this area. NOTE: MOVING THE MONITOR A BIT WOULD CAUSE THE ENTIRE SCREEN TO TURN OFF OR THE BRIGHTNESS IN 100% OF THE SCREEN GOES OFF. He insisted that the backlight led strip must be changed and that some of the leds are burnt, BUT I don't understand why moving or shaking the screen a bit would cause the entire monitor to go off.

Pease help and thanks. If you need more information do let me know.

EDIT: Here's some photos taken yesterday before taken the display to the repair store https://imgur.com/a/SbNhE. The repair dude soldered that female connector in place and I tried puting and pulling the connector and it seems good.