When i plug in my laptop. it'll turn on for 3

Try replacing the power cord, if the problems still persist, check the wall outlet, if it's in good shape, check for the battery, is it full or empty.

To check the battery, try to switch on your laptop without plug in your power cable to outlet.If the laptop's on, you should replace your charger unit for the laptop, that's the cause.

i think which device has you connected there is some problem check your device then will your problem will be fix