Chosen Solution
Hello, my iMac isn’t turning on after I reassembled it. The testing LEDs work weird: When I connect power cable to iMac LED 1 is blinking 1 time and then turning on. When I press the power button, LED 1 is turning off. No other LEDs are turning on. The PSU unit is making some humming noises when is connected to power What could be a reason for such a behaviour? Thanks a lot for answering!
Your power supply is not working correctly. As to why given what you’ve added I would suspect you have either a damaged cables or a bad SSD. Best to backwind your changes, disconnect from the logic boar the cable connections are you belt o get the onboard diagnostics to get to the graphics test (without the display mounted).
