Answer Description

The symptoms describe a failing inverter, which provides power to the screen's backlight.

Wikipedia

A laptop computer or notebook computer, also known as a laptop or notebook for short, is a small, portable personal computer (PC). Laptops typically have a clamshell form factor with a flat panel screen (usually 11–17 in or 280–430 mm in diagonal size) on the inside of the upper lid and an alphanumeric keyboard and pointing device (such as a trackpad and/or trackpoint) on the inside of the lower lid, although 2-in-1 PCs with a detachable keyboard are often marketed as laptops or as having a "laptop mode". Most of the computer's internal hardware is fitted inside the lower lid enclosure under the keyboard, although many laptops have a built-in webcam at the top of the screen and some modern ones even feature a touch-screen display. In most cases, unlike tablet computers which run on mobile operating systems, laptops tend to run on desktop operating systems which have been traditionally associated with desktop computers. Laptops run on both an AC power supply and a rechargeable battery pack and can be folded shut for convenient storage and transportation, making them suitable for mobile use. Today, laptops are used in a variety of settings, such as at work (especially on business trips), in education, for playing games, web browsing, for personal multimedia, and for general home computer use. The names "laptop" and "notebook" refer to the fact that the computer can be practically placed on (or on top of) the user's lap and can be used similarly to a notebook. As of 2022, in American English,