Why is my laptop isn't switching on properly?

I give two possibilities: either your CPU is stressed and damaged, or Windows has a problem, an expert should test your laptop.

@selvarajah79992 could be a thermal issue. What have you checked? Can you still get into your computers BIOS? Hit the F12 key on startup and see if you can get into the BIOS. Also, you did not tell us if it behaves the same when it is connected to the AC adapter or only when it runs on battery.

Start off with the easy things. Disconnect the power from the computer by unplugging the power cord from your computer. Disconnect all external devices from the computer. Now hold the power button depressed for about 30sec-1min. Reapply the AC power adapter and see if your computer does show any sign of life.

Next you want to check your power supply. Make sure it has the proper voltages. Check to make sure that the connectors are not bend etc. Check the DC-in jack of your laptop. Make sure there is no corrosion, debris etc. that prevents it from working. Clean it of any debris etc, use a few puffs of air to clean it out. If none of this works, get an ammeter and see if your laptop draws any amperage from the charger. After that, you need to check and see if your motherboard even gets power. For that of course, you need to open it up. Post Some good pictures of what you see. That way we can see what you see.

Of course, it is also possible that this is a bad RAM module or a bad LCD. So remove the RAM, clean the contacts with a pencil eraser. Do it gentle so as to not destroy the module. Replace it and restart. If you have more than one module, remove it and just leave one connected.

Let us know how things are working out with each check/test.