New PSU died on first boot

Jan 8, 2017
CPU: Intel Core i5-6600 3.3GHz Quad-Core Processor
Motherboard: Asus B150I PRO GAMING/WIFI/AURA Mini ITX LGA1151 Motherboard
Memory: Kingston FURY 16GB (2 x 8GB) DDR4-2133 Memory
Storage: Kingston SSDNow V300 Series 120GB 2.5" Solid State Drive
Storage: Seagate Barracuda 2TB 3.5" 7200RPM Internal Hard Drive
Video Card: MSI GeForce GTX 760 2GB TWIN FROZR Video Card
Case: Fractal Design Define Nano S Mini ITX Desktop Case
Power Supply: Fractal Design Edison M 550W 80+ Gold Certified Semi-Modular ATX

The “Fractal Design Edison M” is manufactured by Seasonic.

I built a PC with mostly new parts. SSD and GPU are old. The old parts I removed myself from an old computer and they were working beforehand.

No particular issues during assembly. At first boot however the PSU immediately made a pop sound, I saw flashing/arcing in the PSU (it was facing me) and smoke.

I never heard any fans start or see any LEDs blink.

I disconnected everything from the PSU and did the paperclip test with case fan as only load. PSU is stone dead and I hear a crackling/arcing noise inside when power is on.

PSU was connected to a grounded socket during all testing (230 VAC @ 50Hz verified with multimeter).

The build was done using an antistatic chain connected to the chassis. The PSU connected to a grounded wall socket with flick switch in OFF position.

Packaging was undamaged. PSU was never dropped or exposed to overvoltage by me.

I suspect it was DOA, but fear I might have done something wrong? I don’t understand how that could happen, though. This is not the first time I build a PC. I double checked my wiring and the only fault I found was that the “hard drive working” LED on front panel was installed with reversed polarity.

I was able to test the HDD and SSD on my old computer. They are still working. Cant test the MB before I get a replacement PSU however.