1. The characteristics of the high-voltage board in the display part of the laptop are poor, which is generally the virtual welding of the collector of the power tube or the primary or secondary virtual welding of the booster transformer;

2. Circuit failure of backlight lamp, such as oxidation of a lamp pin, poor contact, etc.

If you have hands-on ability, you can open the back panel of the notebook and carefully check the situation of the high-voltage board and its backlight circuit.