Réponse à : « MacPro does not power on... and does not attempt to boot »Having the same problem. Mac Pro 2012 (2 x 6 core). During storms in Sydney a week ago we had a power surge. TV acted strangely for a while the next day but eventually recovered. Thought nothing more about it. A few days later Mac Pro started to refuse to wake from sleep state (breathing LED). Then yesterday refused to power on. No front white LED, no clicks, chimes, fans internal LEDs - nada! Seems utterly dead. However, pushing the diagnostic button on the backplane near the Front USB card causes one orange LED to appear. Seems like the consensus is one of two solutions - new motherboard or new power supply. Both are big $$$, so any further thoughts would be appreciated!