Laptop powers down after ~10 seconds

My little sister bought a laptop a year ago, and like all cheap laptops, it started acting up after a month or two. Today she tried to turn it on, and all the lights came on, but the screen didn't display anything and it turned off after 10 seconds, only to try restarting on it's own again. It tries to restart every time it shuts down.
I've tried running it off only the battery running it off only the outlet, running it off both the battery and the outlet, holding down the power for five seconds to shut it down before it shuts itself down, and letting it rest for a minute or two, followed by all of the above. Is there some easy fix I'm missing?
If there's any technical info needed here, it might be: the laptop is a Dell... But that still shouldn't have any effect on the situation.

 

1. Do you hear any beeps?
2. Have you tried tapping F8 at boot up to see if you get a menu?
3. Do you know what key you must press to get into the BIOS?