Thanks for the revert DVDdoug,
The Kanthal wire I have has Resistance (Ohm/FT @ room temp): 10.55. Using Ohm's Law, if I supply 5V, I need current of 0.47393 amps.
So battery should be able to provide around 0.5 amps of current. Right ?
Yes, you are correct I have fried the transistor!
I didn't quite understood heatsink. Can you please help me understand what I need to do so that transistor/MOSFET can withstand the heat (based on the circuit diagram)?
Sorry for my brevity!