dell optiplex 3020 power adapter power trips when plugged in to the computer

Please help it worked fine for a while after my daughter knocked it of the side but now it won't power on

I've tried different power adapters and still does the same thing

No power makes it to the computer at all, the yellow/ green light on the power transformer just goes out when it touches the computer is there a safety switch on the mother board ?? I've tried it with everything disconnected