I had the "stun" issue dogie mentioned a few times and strangely turning off the PSU with a switch didn't help. I had to unplug it completely and start again. Looks like some of them have built in breakers that get stuck in an off position as long as they detect current.
The paper clip is probably ok, because he said the PSU turns on and then off after a few seconds, so you should look for the problem in the miner, or the PSU is just "too sensitive".
Additionally you have to let the electricity drain from the PSU's capacitors for several minutes until they are completely empty. The PSU should then reset when plugged in again. If the issue persists there may be a short that is being detected by the PSU and it's cutting power in order to save hardware.