1. First of all, let's conduct a comprehensive inspection of the connection between the computer monitor and the host, and plug all the connections to see if there are any connection problems.

2. If the fault still exists, then we need to open the chassis to see if it contains metal and other substances, causing the computer host circuit to be short-circuited. Then we smell the computer to see if it smells burnt, and if there are damaged components around the motherboard and CPU.

3. The whole chassis was checked, and there was nothing abnormal in the chassis, so we treated the dust in the chassis.

4. If you can't boot, then unplug the data cable of hard disk, floppy disk drive and CD-ROM drive with the minimum system method, and then check whether the computer can boot. If the boot screen appears on the computer monitor, it means that the problem is with these devices. Then connect the above devices to the computer one by one. When the equipment is connected, the fault reappears, indicating that the fault is caused by the equipment. Finally, focus on checking this equipment.

5. If the fault still exists, it is probably the fault of memory card, graphics card, CPU, motherboard, etc. At this time, we just need to plug and unplug these hardware, or replace them again, and try to find the reasons one by one.

6. If the memory, graphics card, CPU and other equipment are normal, then discharge the BIOS, adopt the isolation method, put the motherboard outside the chassis, connect the memory, graphics card, CPU and so on for testing, if the computer can display, then put the motherboard into the chassis for testing until the cause of the failure is found. If the fault still exists, the motherboard needs to be returned to the manufacturer for repair.

7. When the computer is turned on, there is no display, but there is an alarm. When the computer is turned on, the system BIOS will start POST. When the device in the computer detects a fatal error, it will control the speaker to make a sound to report the error. Therefore, there may be a failure without alarm sound when starting the machine. There is no alarm when the computer is turned on. According to the meaning of BIOS alarm sound, you can check the faulty equipment and troubleshoot it.