@Osprey
Thank you for youre reply. As you suggested, I have browsed through the troubleshooting manual, but none of the solutions can help in solving the problem.
I am unable to run Dell diagnostics. The reason is that the computer shuts down by itself during BIOS, as if there is an electrcial breakdown, which there is not. If I choose to run Dell diagnostics, it will not be able to complete the diagnostics, before shutting down without any apparent reason.
None of the power lights on the front panel (showing 1, 2, 3, and 4) were switched on, thus the computer does not indicate the source of the problem.
As of now, I am unable to solve the problem. So, what should I do now?
Thank you for the advise. :)