They are fragile, which is why I posted this in one of your earlier threads:
"General comments on display removal: be very careful with the bonded ribbons - try not to flex them much. If the display is held down with double sided tape, make sure to carefully life the screen out. I use a heat gun (carefully) to heat up each side one by one, and with a small suction cup, pull up while sliding a thin plastic shiv along working until the side is free.. If you try to lift the screen without releasing the tape, the screen WILL crack. Make sure those sheets go back *exactly* as they came out. If you get one upside or backwards or out of order, it will affect the picture as at least one of the sheets is a polarizer. Make sure the four corners of the display itself are safely nestled inside the frame. You can use a combination of feel and magnification if necessary to make sure the screen isn't sitting on the lip even by a micrometer. If the display isn't tucked properly inside the frame, it WILL crack when you snap the outer mask back in place."
If it's any consolation, I've walked dozens of people through LED repairs on-line, and I honestly can't remember more than one or two at most that did not suffer a screen failure.
Also, just because the TV presented with bad LEDs doesn't preclude the possibility that it was broken before you even attempted it.
When I do an LED job, I look over the screen carefully with a bright light looking for a cracked glass layer under the outer dark tinted plastic layer which does a good job of hiding an internal crack. If that looks OK, I remove the screen and hold it up over my head like I was presenting a gift to the Gods so I can spot a crack against the backlighting of my shop fluorescent lights. If there are no visible cracks, I keep going.