Black screen even after replacing

This is the second time I've replaced my screen. The first time it went perfectly but this time I'm absolutely lost.

Problem. Cracked screen, replacement screen will not show/is black.

What I have done so far:

Safe mode

FDR

Flex cord replaced

Removed all components and checked for damage, including checking for damaged pins on the connector.

Sent replacement screen back and exchanged for another wich came with another new flex cable so I replaced that again too.

I am able to plug in an hdmi into it and can display it on my tv. Doing so I am able to see that it responds to touch and my spen.

Everything on the tablet seems to be working fine except the screen displaying an image and remaining totally black.

How can I resolve this issue?