*me mysteriously appears in a puff of smoke*
That DC motor circuit I assembled over the weekend worked fine.
I left the batteries inside the battery casing over the weekend,
and nothing wrong happened.
Just then, when I reached school some time ago, I realized that
the batteries were overheating. I quickly took them out to leave
them to cool down.
I was like, WTF.... the circuit was switched off, and there were
no short circuits (I checked).... why were the batteries
overheating?!?! 
I guess everything electronic that I touch is doomed to die.....
even if I had built the circuit myself.
