Dell Latitude 7400 Screen Flickers

There is a continuous flashing of the Dell Latitude 7400 display.

An old or damaged screen typically when the device is not new could be a reason for a flickering display. First, confirm the issue by connecting an external monitor—if that display works fine, the laptop screen is the problem.

Linked here is a video tutorial on how to replace the screen.

The Windows Task Manager is a built-in tool that lets users view and manage active applications, monitor system performance, and identify or terminate processes that may be causing problems. To open the Task Manager on your Dell Latitude 7400, simultaneously press the [Ctrl] + [Shift] + [Esc] keys.

If both the screen and Task Manager are flickering, it may indicate a display driver issue.

Press the [Windows key] + [Ctrl] + [Shift] + [B] simultaneously to reset the graphics driver. You will hear a short beep sound, and the screen may briefly turn black
If the issue persists, open the Task Manager and open the Device Manager
Select Display adapters
Right-click your graphics card and choose Uninstall device
After you have completed those steps, restart your laptop to reinstall the display driver automatically

If your screen flickers and your Task Manager does not, the issue is likely an incompatible application

Open the Task Manager and check for any unfamiliar or recently installed programs that could be causing issues
Update all applications to their latest versions and uninstall any that are known to cause flickering, such as Norton antivirus or iCloud
Install any pending Windows updates, as they often solve software conflicts that can lead to screen flickering

Flickering can also be caused overheating or power issues. These issues often result from the GPU or display losing stable voltage or throttling under heat stress causing the base to get hot.

Here is a link on how to fix this problem.

A flickering screen on a Dell Latitude 7400 caused by an outdated or corrupted display connector usually means the internal video cable (LVDS/eDP) is loose, damaged, or dirty.

To repair it: power off the laptop, remove the back cover, and carefully locate the display cable near the hinge. Reseat the connector by unplugging and firmly reconnecting it, ensuring no dust or corrosion is present—use isopropyl alcohol and a lint-free cloth if needed.
If flickering persists: the cable itself may be frayed and should be replaced following Dell’s service guide.

First confirm the issue by checking if the flicker appears in the BIOS, Dell ePSA diagnostics, or on an external monitor—if it does, it’s hardware-related.

Start by reseating the internal components: disconnect the battery and display cable, then reconnect them securely. Next, update or reflash the BIOS from Dell’s official support site, as firmware corruption can sometimes cause display instability.
If the problem persists, the motherboard’s integrated GPU is likely failing, and the only permanent repair is to replace the entire motherboard. Professional repair is recommended, though a temporary fix like GPU “reflow” or using an external GPU via Thunderbolt can serve as short-term solutions.