Upside Down Uk Plug
Is there a 3 pin 13A socket in which the cable is going to the top socket instead of the bottom? 3
I've never seen it before. The solution is to flip the connector.
It's not running again. I saw a snapshot of the PSU where the cable came out from above. The plug is designed to prevent the cord from being pulled out of the socket if the cord breaks.
There is no point in going in or near the floor if the wires can connect, but I don't think so.
You just turn off the power, unplug it from the box, and rotate it to face it. You may not even need to unplug the cable.