Chosen Solution
My Mac suddenly can not turn on. As I know how to fix computers, disassemble and check the components, I have noticed that the LED 501 on the left, is constantly blinking some idea that it can be
While not shown in the IFIXIT 27" guides this iMac Intel 24" EMC 2134 and 2211 Diagnostic LED’s guide goes get into the diagnostic LED’s used in all of the newer iMac’s. Jump to Step7 for the full writeup on them. As to why your LED #1 is blinking, I would test the power supply to see if you have steady voltage. I suspect you have a bad power supply.
