please help

I had XP on my computer. I reformated it and installed windows 7. Now when I push the button to switch it on it keeps rebooting after about 4 to 5 seconds. It reboots between 3 to 5 times then switches off. The computer doesn't even comunicate with the monitor, I get no images at all on the screen. So I cant tell if I am getting any error messages. I have tried taking the power cable out off the back and holding the power button in for about 5 seconds to discharge the power unit but that makes no difference at all.

Please help

col

Hi,
Please turn off your computer and unplug from electrical power, open the computer case and took out battery for 10 minutes.

After that, please put it back and let me know if you're able to turn it on.