In this video I will do my best to explain what goes on when you turn your laptop on and off.
The common reason why a laptop doesn't work anymore is due to the resistors in the charging and power circuits inside a laptop.
If you are the type who leaves your laptop in sleep mode that will also shorten the lifespan in your laptop.
Just switch it completely off and the reason why you want to do this is because your laptop is still discharging while asleep which causes resistor failure over time.