You shouldnt have opened up your computer, If you had any warrenty left it would now be void, so taking it back to the shop is out of the question! Doesnt seem like a PSU related problem, cant say as i think its short on power, I have the same PSU rating but with bigger components
. Sounds to me like you got a faulty HDD, try sending an email to the manufacturer, they'll probebly be more than happy to send you a replacement!