Chosen Solution
Original issue: No picture over built in and external monitor. Current issue: Won’t turn on - But holding power on button while plugging in let’s the fans run at 100%. What led to from issue 1 to 2: According to the internet baking the gpu could fix the soldier points (eg broken ones). In my case a resistor came off and i had to solder it back on. After putting everything together, the iMac won’t turn on. LED1 on the logic board is illuminated. Disassembled, reconnected everything and reassembled it, but the iMac still won’t turn on - other LEDs are still off and fans are not spinning.
Sorry your GPU board is gone you’ll need to replace it. The oven trick doesn’t always work as you’ve discovered. Here’s your options: AMD Radeon HD 6750M 512 MB - 661-5944AMD Radeon HD 6770M 512 MB - 661-5945
