@patrix @grgarside Thanks for clarifying. So it all gets down to the possibility of resurrecting some sort of blog.

Wow, so quiet here nowadays :-(

Also @bmike I wonder whether I should add, to the question, a note that the Mac no longer responds to its internal keyboard or trackpad – an issue that arose not long after replacement of the main board under Apple's free programme for that class of Mac (note to self: find the link).

@GrahamPerrin It is a tough call. You have already packed so much detail in that - it's not clear if you're just looking to research it and come back with an answer or if you want someone to take a stab at answering one of the many questions in the body.

I deleted my answer since I initially didn't see you had linked to most of what I had to say on the topic.

I don't think you'll get Intel or Apple to document the design decisions, but it's clear the firmware on MacBook line is mostly crippled without a fully operational sensor suite (battery and sensors) and fully reporting in as OK battery to cover current spikes the power supply can't provide.

Unless you could get Mac mini or iMac firmware on that logic board and beef up the power supply -my guess is the CPU is going to be underwhelming, SIP or not.

Intriguing that you've managed to cobble together a situation showing potentially a SIP involvement (whether it's to modify the protected kext / confugration) or part of SIP explicitly

Thanks. Plus a few minutes ago I realised that the unexpected stop of the Mac probably left some cruft in NVRAM; the keyboard backlight was on (and uncontrollable, because the keyboard is unusable, LOL) so I just did a reset (unavoidably re-enabling SIP) followed by Recovery OS 10.13 to again disable SIP :-)

It's an entertaining Mac. I keep it only for test purposes. Could/should have returned it to to the local AASP for the specialist test when the board replacement was followed, so soon, by the keyboard/trackpad issue but I just never got round to it.

(What's that test called, the one that only Apple and AASPs can run? Involving NetBoot …)

@GrahamPerrin MRI is the internal name - Mac Resource Inspector or something for the quick diagnostics.

The self servicing accounts and enterprise AppleCare plans came with that tool (or that was on the Apple web site in the past - not sure if it's still available).

support.apple.com/self-servicing-account-program

> 3. Confirmation of a dedicated diagnostic server, i.e. Mac mini or equivalent

apple.com/support/enterprise

Interesting links you found - looks pretty detailed and some of those screens are familiar when I brought my devices to a Genius Bar / Apple Retail store for service.

The iOS diagnostics can run when you are anywhere - I've had Apple Support send a link to diagnostics over SMS / mail and run the iOS diagnostics remotely. We don't see the results, though in that case.