There are many reasons why the computer can't be turned on, which should be analyzed and eliminated one by one:

1, whether the computer host and monitor are powered on. If there is no power, turn on the power connection switch and turn on the power. Then check whether the power supply of the motherboard and the main chassis is normal (the main chassis may have a power failure).

2. If there is electricity, check whether the connection between the monitor and the host is intact, or plug and unplug the video cable again.

3. If it doesn't work, check whether the video card is loose and plug it in again (wipe your golden finger).

4, unresolved, try a different graphics card if possible (there may be something wrong with the graphics card).

5, check the memory, check whether the memory stick is loose, plug it in again (wipe the golden finger).

Basically, all the above simple methods can be solved. If not, it is recommended to find a professional maintenance unit and check the motherboard.

I hope I can help you.