last night my pc randomly turned off, it didnt shut down it just went off. when i tried to turn it back on there was a bright flash and a pop at the back of my pc and now it wont turn on at all, i think its my psu but am reluctant to go and buy one if theres a possiblity that its something else. can anyone give me any other reason as to why its done this? any help is appreciated, thanks.