Wipeing out hard drive with magnets?

I have a laptop that has to be return back in the mail for a replacement.
This one fry itself.
I want to know if a magnet that can pull 750 pounds will wipe it clean.
The laptop will not start up.
But I want to make sure that if it gets put into another laptop that all of my info will be gone.

Thanks for your input.
Frogwillie2001@yahoo.com