I just got my subwoofer out of a storage place and found that the on/off switch is not working properly. Basically I can't turn it on unless I unplug it and then when I see the blue light coming on and quickly plug it back in. And it can stay on the whole time. But when I connect it to my receiver, I don't hear any response and it quickly overheats. So is my subwoofer basically useless now? Thanks for your answers in advance.