So the computer was running fine until I decided to plugin a external drive via the usb. I didn't even get to insert it, as soon as the usb touched the usb port, the computer shut off and there was a weird loud crackling noise from the Power supply unit. I unplugged everything and back in, the loud crackling is back.
When I press power button, the computer momentarily starts then immediately shuts off. I press it again and same thing. with the regular loud tick sounds every 2 seconds.
how to fix this and what has happened or happening?