See if you can borrow a psu that you know works, and plug that in and if everything works then you just need to buy a new psu, other wise the motherboard is probably toasted, check for any signs of burning on the board, and you will probably have to replace it.
Although if you brought the computer whole from aria and you did everything like you were told then it should be covered by the warranty
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did it come with instructions?
Edit: If it came with no instructions then you can complain because most people wont know about the voltage changeing switch