Is No Led Light On Logic Board Always Translate To Bad Psu Imac Intel 27 Retina 5K Display

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I have the 27inch imac recently notice not powering on. i open it to check the logic board light is not on.. ALL 4 LED light not on. I suspect power supply failure.. order one replacement but still no LED after replacement.. i wonder is logic board issue?

Cord and the socket are also suspect!