Chosen Solution
Hi, I got this iMac to fix and I have been having a really hard time. When I plug it in led 1 blinks twice but never fully turns on, it only does this when I plug it in then it imminently stops. The PSU does make a slight buzzing noise but nothing noticeable. I have replaced the PSU with a newly bought one from eBay. I have already also tried different RAM. Here is a video of what happens when i plug it in.
You have a short in one of the power rails within the logic board. This could be a blown GPU board or a cap has failed. You’ll need to remove the logic board and inspect it and the GPU boad for any burnt or damaged parts.
