What to fulfil if a laptop won't power on. what else is there to try?

Hello, my sister has a Compaq Presario 2500. Won't power against. I told her to endeavour plugging it in to another outlet, still will not power on. Told her to take out the battery and use the power cord, still will not dominion on. She is in another state, then I generally would open it and see if the power supply went bad. There is a reset lever, told her to hold that down for 30 seconds. Don't know why, but I told her to hold the power button down.