I don't know if you are a Mac guy, or have a mac guy working on it for you, but I worked on Macs for three years and have always had success getting them going with minimal work. If you need some help, I'd be glad to offer what little I know.
If it is a 2010 or later Mac, the built-in solutions for repairing have always worked for us (we had about one hundred of them). Every week or o we would have one or two blow up, and it was generally a malfunction in the SMC, and when it wasn't that (rarely) a reinstall (format) always solved it. You can find the specific directions for your model to reset the SMC if you haven't tried that on Apple's site,
. It takes about 30 seconds to give it a shot. The PRAM gets crazy sometimes too, and
how to reset it.
2015 Red/Black Honda NC700X
2015 Brownstone Metallic Chevrolet Colorado Z71
2006 Black BMW F650gs
1998 Ascotgruen Metallic BMW 318i - LS Swap Project
1988 Grand Prix White Porsche 928 S4 - Almost There
1967 Marina Blue Chevrolet Camaro - Project
1957 White Chevrolet 4400 Flatbed - Project