Chosen Solution
Hello, Recently I replaced the NVME SSD in A1419 iMac. Unfortunately, it did not turning on after doing that. I replaced the new PSU, but the same situation. It seems PSU is OK. AC-DC connector, J600 #4~6, #10~12 are 12V. But 4 diagonostic LEDs in logic board are not turning on. What shall I do check for the first time? I want to repair by myself… but not board view file for this model. Please let me know the solution and share the borad view file, if you have. Thank you!
I would remove the drive you put in it’s likely bad or shorted out. Carefully plug things back together without the drive and any adapter does the system boot up now? If it does then you need to replace the drive elements. I would recommend going with a better drive like OWC Aura Pro X2 SSD
