I just found a way to a hard reset of the N900. And it works effectively.

Here is the step you should take to achieve this so called Hard Reset.

1.Pull out the battery from the device
2.slide the keyboard out
3.grab a cup of coffee
4.A hammer
5.Pour the coffee on the keypad and the back of the battery section
6. This step is the Hard Reset step, place the N900 on the concrete floor or Hard wooden/stone table and swing the hammer repetitively on to the N900 screen and keyboard and turn the N900 around and keep at it until the device fully re-SET itself and you will see no more Nokia Handshake video will show up ever again.

Now perform a CPR like you did on a human being and resuscitate the device.

Done..

Do it at your own risk, due to this guide required a lot of professionalism and 100% failure of resuscitation of the device, I would recommending you to have a second thought about trying to do a Hard Reset on this device.

Good luck, may god keeps your N900 safe