You need to unplug the battery then plug it back in to ensure the phone is switched off then you can plug in a replacement screen and turn on the phone. It should show display after that.
If the screen is plugged in while the phone is still turned on I don’t think there will be display on the screen until you hard reset the phone.
-
If no good still inspect around the screen connector on the board for any pry damage (missing components
+
If no good still inspect around the screen connector on the board for any pry damage which are missing or dislodged components.
You need to unplug the battery then plug it back in to ensure the phone is switched off then you can plug in a replacement screen and turn on the phone. It should show display after that.
If the screen is plugged in while the phone is still turned on I don’t think there will be display on the screen until you hard reset the phone.
If no good still inspect around the screen connector on the board for any pry damage (missing components