Chosen Solution
Hi Guys. OK never seen this before. Client brought this in won’t start up so first thing to try is battery but it would seem thats not the issue So i open it up & see if there are any signs of liquid damage ETC disconnected battery connected to power tried to start it up. None of this worked so i reconnected the battery & connected to power the fans started spinning. Took it off the battery with just magsafe nothing just connected to battery nothing but when connected to both the fans spin up Mac still doesn’t boot. Before i start searching the issue down as this could be time consuming has anyone come across this before & did you get a resolution? Yes i’m being cheeky I’m going on holiday on weds so time is tight. Thank you in advance
With the charger plugged in and battery disconnected, listen for clicking on the logic board. I have seen a number of 2012 15" models where they go dead for no reason, and the issue is related to a couple of mosfets on the back of the board. From memory they are related to the 5V DRVL signals. Otherwise check for liquid damage. Try to ultrasonic it in a good cleaner, could be a small amount of liquid under the SMC causing intermittent issues.
