Steve

Hi iFixit, thanks for an awesome website. My MBP 15" A1260 is coming up on 4 years. Instead of dropping serious cash on a...

Did you have any luck with this? I have a Mac Pro 4,1 (single CPU) that is exhibiting the same symptoms. It was on 2 days ago, now no power on at all. UPDATE 07/12/2017 Hi Max Entropy! Thanks for the quick and detailed reply. (I'll stick to replying to this thread, instead of starting new answers...) I, too, have a second working machine, but I've yet to start the process of swapping components. My hunch is the same as yours — a surge has damaged the power system on the backplane board. The diagnostic button shows 5V on the backplane board, but jumping the SYS_PWR jumpers has no effect, which is all the detail that the Apple technician guide goes into. So, I don't have any questions right now, but I would be very interested to hear how your new power chip works out. Thanks again.