Why is it not oning

Basically there are few steps you can try:

1. UNPLUG the laptop power adaptor from the power jack
2. REMOVE the laptop battery from the laptop.
3. OPEN the back cover of the laptop, if found/can see CMOS battery, REMOVE it too.
4. PRESS and HOLD the power button for at least 10 seconds ( for fully decharge and clear the power within the laptop)
5. PLUG back in the power adaptor, try to POWER ON the laptop and see

If it doesnt work, then you need to find professional technician to diagnostic thru the laptop or if you got experience, you can try to dismantle the laptop and check thru is there any fault on the motherboard, connector, or any components inside.