Replaced screen and no backlight

Hello all,

Iv read a couple other posts but nothing seems to be working

I have a Late 2013 MacBook Pro Retina with a cracked screen.

I replaced the whole screen assembly with another screen from another late 2013 MacBook Pro retina.

For some reason the new screens backlight isn’t working.

The new screen worked when it was connected to the donor laptop but won’t work on the laptop I’m attempting to repair.

I shine a flashlight through the apple

Logo and I can see the desktop so it’s forsure the backlight. Is there anything I could have done wrong.

The serial number for the laptop I’m fixing is C02ML99WFGYY and the serial from the donor laptop is C02MPA5UFH00

Please help!!

EDIT: when I put the new screen back on the donor laptop, the backlight doesn’t work now. So either I’m installing something wrong or I fried the backlight somehow on the new screen