Does it make the snapping noise every time you power it up or did it do it once and then just died basically?
Sketchy power supply source + sketchy variable
power supply = you fried something. Thats my opinion anyway
I would assume you killed a control IC. I did the same thing to a computer PSU that I was modifying to be a bench top power supply. Accidently shorted the 5vdc trigger wire to the 120vac line
destroyed the IC but I couldnt tell. There was no smoke what so ever and there was also no visible damage to the IC. I looked up the datasheet on the IC that was closest to the trigger wire and found out it was the power cycle changer thingy...(basically responsible for telling the PSU to let the juice flow). I found another PSU that used the exact same IC and just swapped the IC out and it worked perfectly fine after that. The IC was an 8 pin IC that looks exactly like a 555.
Hope this helps at all.