DE2 board burnt

Hello,

I have been using an DE2 board. While the main switch(sw18) was turned off and the apadtor was connected to the power I heard a noise(like hissss...) and smelt the usual smell when an electronic device is burnt. Surprisingly the most strong smell was coming from the USB blaster port, the DE2 board is not functioning after that . When I used a multimeter to check the voltage difference between the incoming port where the DC jack is connected I found out it was 1.5-2V though adaptor was still supplying 9V. I wonder is how it gets burnt when the switch is not even turned on!!! And is it possible to get repaired?? I am from Bangladesh and it is quite difficult to get all the spare parts. Could anyone help me on this regard?