Solved! I have msi i5 3rd gen it switches off in just 18 - 20 seconds why

[majerimansiyambonga]

My laptop msi Just switches off in few seconds yes my battery is dead but even if I use a power cable it does the same

 

[hang-the-9]

Most likely issue is a dead motherboard. Could be an issue with the power supply also. You can try different RAM. Check to make sure it's not overheating, clean it out, apply new thermal paste to heatsink. If your system has a removable MXM video card you can try to remove that and see if it works with the onboard Intel video.