Chosen Solution
Hey Guys I currently have an iMac 21.5" 4K Late 2019. The iMac will not turn on. Diagnostic LED # 1 lights up when the Mac is powered. There are no fans running. Power supply is fine. Someone an idea?
What transpired before you opened the system? Was it working and stopped after doing something? Have you taken the logic board fully out to inspect it for visible damage? I suspect its time to pull out the schematics and board view drawings to trace out the power rails.
