Since overheating can take place in less than 1/10th of a second, do not bank on the cold weather temps to keep thinks cool.

When I disconnect the power cable or unplug it from the socket or press the bottom at the back of the case (i.e. when I disconnect electricity completely), I hear a tiny sound of beep like a small crescendo!!!!!! for 2 or 3 seconds and then it stops
Now since the power supply is there, I am thinking it is going haywire. Warranty time in my book since you got it only 7 months ago. May even be put together wrong.