Why does my Dell replacement screen stay black?
On replacing an Inverter powered (CCFL/LCD) DELL laptop screen, you may find that the new replacement screen remains dim or appears completely black. Placing a light such as a torch or desk lamp behind the rear of the laptop screen display often allows you to see the DELL logo and Windows when the laptop is powered on, however the display always remains very dark or appears completely black.
Systems affected
Inverter powered screens
This only applies to Inverter powered screens known as CCFL or LCD screens. These type of screens use a power inverter that sits under the LCD screen. One or two small white plugs come from the bottom right hand side of the screen (when looking from the front). This (or these) white plug(s) attach to the right hand side of a power inverter that sits underneath the screen. Quite often genuine DELL replacement screens come with a frame around the laptop screen that also houses the Inverter.

Example 1:
Here we have an example DELL replacement laptop screen. Note that this will likely differ greatly from yours, but we´re using this one as an example.
Underneath the screen, sits the Inverter, sometimes loose but usually screwed into a bracket under the screen.
Point A - This is where the CCFL Inverter cable comes from the screen and plugs into the Inverter.
Point B - This is a small screw that holds the Inverter in place.
Explaining the problem in more detail
Reason for the problem
Although the screen is compatible, the Inverter on the new screen is not. Inverters can change specification over time on the DELL replacement laptop screen panels and it may be that this revised version of the screen you have received has an Inverter that is not compatible with your motherboard.
Solution
1. Remove the white plug from point A on the Inverter by pulling.
Resolving the issue is very easy, you simply need to swap the inverter from your old screen to the new one.
With your new screen:
2. Unscrew the screw from point B using a small screwdriver.
3. You may need to ease and slightly bend the bracket to ease the Inverter out.
Now repeat the process on the old screen and swap the Inverter board across.
Further issues
If the old Inverter board does not fit into the frame on the new LCD panel you can usually remove this bottom bracket from the LCD screen and leave the Inverter loose under the display. This is perfectly okay as the Inverter is fully shielded.