What is it that the computer calendar doesn't show the time but the light is still on?

Open the back shell: 1. Check whether the switching power supply or transformer connected to the display panel is in poor contact with the 220V line. 2. Check whether the switching power supply or transformer connected to the display panel is damaged. 3. Check whether the connected switching power supply or transformer is in poor contact with the wire of the display panel. 4. After the above problems are eliminated, check the display panel. Is the rectifier circuit, capacitor 470- 1000 UF or 7805 voltage regulator damaged? Crystal oscillator 32768HZ damaged and unable to vibrate? According to the above steps, the fault can be eliminated, but when the equipment needs to be replaced, please solve it yourself. Please ask a professional to repair the above content, because it involves 220V voltage.