Compaq Presario turns on for about a second..

I have a Compaq Presario laptop. Today, I put it in sleep mode and ran some errands. When I came home, it would not come out of sleep. I turned it off and back on. It came one for about a second and acted like it had no power and shut off, then lit up again, acted like it was about to start, clicked and all the buttons went dark again. It does this roughly five times and then just stops. The battery has been dead for a while, so I just run it off the power cord. I unplugged the power cord, took out the battery, and held down the "on" button for 30 seconds, plugged it back in without the battery and tried to start it and it's still doing the same thing. Can anyone help?