Problem with Dell 1545

I have a Dell 1545 and i have been experiencing all kinds of problems with it.

First, about a week ago i turned on my computer, and saw the following error " One of your disks needs to be checked for consistency"

Then after that happened, it was not able to check when the scan was run, the scan didnt work.....The computer completely shuts off when you use it. So i reformatted the hard drive, reinstalled windows, and then the same thing happens. I thought it was the hard drive so i replaced the hard drive, and it is still shutting down completely randomly.

I clean out the vent in the back, there is no hair, and it does not get hot.

When it shuts off, it wont turn back on, unless you remove the battery and put it back in. Now it wont even make it to the home screen, it will just shut off before it loads. I tried to run the F12 diagnostics, but it shuts off when its running. I dont understand what is wrong with this computer.

If anyone has any idea, again i have a brand new hard drive, and the computer is just turning off by itself. I dont think it is the battery because first, the battery has life in it, and 2nd, why would it turn on again when you take the battery out and put it back in the laptop?

NEED HELP!!!!! PLEASE