Chosen Solution
My iMac won’t power on. I’ve tried all the simple stuff - power is good, reset SMC, but still no avail. What can I do next? I’m tech savy and have worked on computers my whole life but never has an issue with my macs like this before. Any next steps would be greatly appreciated! Just to make sure I’m not making a simple mistake - what I’m pointing to on the logic board is the LED’s correct?
Tell us what the LED diagnostics light to the right of the RAM slots are indicating. LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty. LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly. LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement. LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.
Just had the same problem after installing an SSD. Make sure that the power button cable is not severed. Mine was. Once I took the two button cables and connected them, it turned right on. In order to fix it, you’ll have to push the physical button out of the back casing. NOTE - It looks like you have to unscrew the button from the frame (which looks impossible, and is), so don’t try to do that. It is only held in by some pretty strong glue, so take your time, but it will just push and wiggle out. Once you have it out, there are 3 screws as a guard for the circuit. Take those out and you will have access to the leads, which you will need to re-solder the cables to. Be careful when removing the broken wires from the leads!! *** I almost tore one of them off very easily, so be patient. Once done, screw the circuit guard back onto the frame of the button. I superglued the cables to the hole where the frame that it comes out of, but don’t do that if you worry. Once screwed back together, test it to make sure that you fixed it. If it works, you can wiggle it back into the casing and reassemble the machine. Stupid mistake, but took me 3 days to consider that as my mistake. This is so you won’t be plagued for as long.
