If you are experiencing screen flashing / blinking continuously.Try these steps.
Run the LCD Diagnostics on your laptop
To run the Built-In Self-Test perform the following:
Turn the computer off.
Press and hold the D key while pressing the power button. This will start the BIST.
The screen will display multiple flashing colors. Look for lines, distortion, flickering or any other video issues you have observed.
The laptop will restart when the test is finished.
Also, connect an external monitor to your laptop and check if the external display also flickers.
check if the screen flickers on the BIOS page.
Steps to enter BIOS.
-Turn off the computer.
-Turn it back on again, start tapping key at the Dell Logo splash screen.
-If the computer boots to windows, turn the computer off and try the steps again.
If the screen doesn’t flicker in BIOS page and safe mode then ,update the video drivers for your computer from the manufacturer support website.