New screen completely black, but can show backlight

Hi!

I recently purchased an iPhone 5 screen assembly (without speaker, camera etc.) and installed it on my iPhone. It was currently drained, so I connected it to my Mac and it showed the charging symbol (the red battery). But then later it went black. I tried:

- Hard/soft reset

- Software update

- reconnecting screen

- cleaning connectors

If I connect my old screen, which is shattered, and then reconnect the new screen, the backlight will turn on. If I try to reboot after doing this, I'm back to an entirely black screen.

{EDIT:

Turns out after a while after reboot, the new screen will show backlight, but still no image.

}

Btw, the touchscreen does not work in any cases.

Thanks for answering.